1 /* GNU/Linux native-dependent code common to multiple platforms.
3 Copyright (C) 2001-2022 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "nat/linux-nat.h"
25 #include "nat/linux-waitpid.h"
26 #include "gdbsupport/gdb_wait.h"
28 #include <sys/syscall.h>
29 #include "nat/gdb_ptrace.h"
30 #include "linux-nat.h"
31 #include "nat/linux-ptrace.h"
32 #include "nat/linux-procfs.h"
33 #include "nat/linux-personality.h"
34 #include "linux-fork.h"
35 #include "gdbthread.h"
39 #include "inf-child.h"
40 #include "inf-ptrace.h"
42 #include <sys/procfs.h> /* for elf_gregset etc. */
43 #include "elf-bfd.h" /* for elfcore_write_* */
44 #include "gregset.h" /* for gregset */
45 #include "gdbcore.h" /* for get_exec_file */
46 #include <ctype.h> /* for isdigit */
47 #include <sys/stat.h> /* for struct stat */
48 #include <fcntl.h> /* for O_RDONLY */
50 #include "gdbsupport/event-loop.h"
51 #include "event-top.h"
53 #include <sys/types.h>
55 #include "xml-support.h"
58 #include "nat/linux-osdata.h"
59 #include "linux-tdep.h"
61 #include "gdbsupport/agent.h"
62 #include "tracepoint.h"
63 #include "gdbsupport/buffer.h"
64 #include "target-descriptions.h"
65 #include "gdbsupport/filestuff.h"
67 #include "nat/linux-namespaces.h"
68 #include "gdbsupport/block-signals.h"
69 #include "gdbsupport/fileio.h"
70 #include "gdbsupport/scope-exit.h"
71 #include "gdbsupport/gdb-sigmask.h"
72 #include "gdbsupport/common-debug.h"
73 #include <unordered_map>
75 /* This comment documents high-level logic of this file.
77 Waiting for events in sync mode
78 ===============================
80 When waiting for an event in a specific thread, we just use waitpid,
81 passing the specific pid, and not passing WNOHANG.
83 When waiting for an event in all threads, waitpid is not quite good:
85 - If the thread group leader exits while other threads in the thread
86 group still exist, waitpid(TGID, ...) hangs. That waitpid won't
87 return an exit status until the other threads in the group are
90 - When a non-leader thread execs, that thread just vanishes without
91 reporting an exit (so we'd hang if we waited for it explicitly in
92 that case). The exec event is instead reported to the TGID pid.
94 The solution is to always use -1 and WNOHANG, together with
97 First, we use non-blocking waitpid to check for events. If nothing is
98 found, we use sigsuspend to wait for SIGCHLD. When SIGCHLD arrives,
99 it means something happened to a child process. As soon as we know
100 there's an event, we get back to calling nonblocking waitpid.
102 Note that SIGCHLD should be blocked between waitpid and sigsuspend
103 calls, so that we don't miss a signal. If SIGCHLD arrives in between,
104 when it's blocked, the signal becomes pending and sigsuspend
105 immediately notices it and returns.
107 Waiting for events in async mode (TARGET_WNOHANG)
108 =================================================
110 In async mode, GDB should always be ready to handle both user input
111 and target events, so neither blocking waitpid nor sigsuspend are
112 viable options. Instead, we should asynchronously notify the GDB main
113 event loop whenever there's an unprocessed event from the target. We
114 detect asynchronous target events by handling SIGCHLD signals. To
115 notify the event loop about target events, an event pipe is used
116 --- the pipe is registered as waitable event source in the event loop,
117 the event loop select/poll's on the read end of this pipe (as well on
118 other event sources, e.g., stdin), and the SIGCHLD handler marks the
119 event pipe to raise an event. This is more portable than relying on
120 pselect/ppoll, since on kernels that lack those syscalls, libc
121 emulates them with select/poll+sigprocmask, and that is racy
122 (a.k.a. plain broken).
124 Obviously, if we fail to notify the event loop if there's a target
125 event, it's bad. OTOH, if we notify the event loop when there's no
126 event from the target, linux_nat_wait will detect that there's no real
127 event to report, and return event of type TARGET_WAITKIND_IGNORE.
128 This is mostly harmless, but it will waste time and is better avoided.
130 The main design point is that every time GDB is outside linux-nat.c,
131 we have a SIGCHLD handler installed that is called when something
132 happens to the target and notifies the GDB event loop. Whenever GDB
133 core decides to handle the event, and calls into linux-nat.c, we
134 process things as in sync mode, except that the we never block in
137 While processing an event, we may end up momentarily blocked in
138 waitpid calls. Those waitpid calls, while blocking, are guarantied to
139 return quickly. E.g., in all-stop mode, before reporting to the core
140 that an LWP hit a breakpoint, all LWPs are stopped by sending them
141 SIGSTOP, and synchronously waiting for the SIGSTOP to be reported.
142 Note that this is different from blocking indefinitely waiting for the
143 next event --- here, we're already handling an event.
148 We stop threads by sending a SIGSTOP. The use of SIGSTOP instead of another
149 signal is not entirely significant; we just need for a signal to be delivered,
150 so that we can intercept it. SIGSTOP's advantage is that it can not be
151 blocked. A disadvantage is that it is not a real-time signal, so it can only
152 be queued once; we do not keep track of other sources of SIGSTOP.
154 Two other signals that can't be blocked are SIGCONT and SIGKILL. But we can't
155 use them, because they have special behavior when the signal is generated -
156 not when it is delivered. SIGCONT resumes the entire thread group and SIGKILL
157 kills the entire thread group.
159 A delivered SIGSTOP would stop the entire thread group, not just the thread we
160 tkill'd. But we never let the SIGSTOP be delivered; we always intercept and
161 cancel it (by PTRACE_CONT without passing SIGSTOP).
163 We could use a real-time signal instead. This would solve those problems; we
164 could use PTRACE_GETSIGINFO to locate the specific stop signals sent by GDB.
165 But we would still have to have some support for SIGSTOP, since PTRACE_ATTACH
166 generates it, and there are races with trying to find a signal that is not
172 The case of a thread group (process) with 3 or more threads, and a
173 thread other than the leader execs is worth detailing:
175 On an exec, the Linux kernel destroys all threads except the execing
176 one in the thread group, and resets the execing thread's tid to the
177 tgid. No exit notification is sent for the execing thread -- from the
178 ptracer's perspective, it appears as though the execing thread just
179 vanishes. Until we reap all other threads except the leader and the
180 execing thread, the leader will be zombie, and the execing thread will
181 be in `D (disc sleep)' state. As soon as all other threads are
182 reaped, the execing thread changes its tid to the tgid, and the
183 previous (zombie) leader vanishes, giving place to the "new"
187 #define O_LARGEFILE 0
190 struct linux_nat_target
*linux_target
;
192 /* Does the current host support PTRACE_GETREGSET? */
193 enum tribool have_ptrace_getregset
= TRIBOOL_UNKNOWN
;
195 /* When true, print debug messages relating to the linux native target. */
197 static bool debug_linux_nat
;
199 /* Implement 'show debug linux-nat'. */
202 show_debug_linux_nat (struct ui_file
*file
, int from_tty
,
203 struct cmd_list_element
*c
, const char *value
)
205 gdb_printf (file
, _("Debugging of GNU/Linux native targets is %s.\n"),
209 /* Print a linux-nat debug statement. */
211 #define linux_nat_debug_printf(fmt, ...) \
212 debug_prefixed_printf_cond (debug_linux_nat, "linux-nat", fmt, ##__VA_ARGS__)
214 /* Print "linux-nat" enter/exit debug statements. */
216 #define LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT \
217 scoped_debug_enter_exit (debug_linux_nat, "linux-nat")
219 struct simple_pid_list
223 struct simple_pid_list
*next
;
225 static struct simple_pid_list
*stopped_pids
;
227 /* Whether target_thread_events is in effect. */
228 static int report_thread_events
;
230 static int kill_lwp (int lwpid
, int signo
);
232 static int stop_callback (struct lwp_info
*lp
);
234 static void block_child_signals (sigset_t
*prev_mask
);
235 static void restore_child_signals_mask (sigset_t
*prev_mask
);
238 static struct lwp_info
*add_lwp (ptid_t ptid
);
239 static void purge_lwp_list (int pid
);
240 static void delete_lwp (ptid_t ptid
);
241 static struct lwp_info
*find_lwp_pid (ptid_t ptid
);
243 static int lwp_status_pending_p (struct lwp_info
*lp
);
245 static void save_stop_reason (struct lwp_info
*lp
);
247 static bool proc_mem_file_is_writable ();
248 static void close_proc_mem_file (pid_t pid
);
249 static void open_proc_mem_file (ptid_t ptid
);
251 /* Return TRUE if LWP is the leader thread of the process. */
254 is_leader (lwp_info
*lp
)
256 return lp
->ptid
.pid () == lp
->ptid
.lwp ();
262 /* See nat/linux-nat.h. */
265 ptid_of_lwp (struct lwp_info
*lwp
)
270 /* See nat/linux-nat.h. */
273 lwp_set_arch_private_info (struct lwp_info
*lwp
,
274 struct arch_lwp_info
*info
)
276 lwp
->arch_private
= info
;
279 /* See nat/linux-nat.h. */
281 struct arch_lwp_info
*
282 lwp_arch_private_info (struct lwp_info
*lwp
)
284 return lwp
->arch_private
;
287 /* See nat/linux-nat.h. */
290 lwp_is_stopped (struct lwp_info
*lwp
)
295 /* See nat/linux-nat.h. */
297 enum target_stop_reason
298 lwp_stop_reason (struct lwp_info
*lwp
)
300 return lwp
->stop_reason
;
303 /* See nat/linux-nat.h. */
306 lwp_is_stepping (struct lwp_info
*lwp
)
312 /* Trivial list manipulation functions to keep track of a list of
313 new stopped processes. */
315 add_to_pid_list (struct simple_pid_list
**listp
, int pid
, int status
)
317 struct simple_pid_list
*new_pid
= XNEW (struct simple_pid_list
);
320 new_pid
->status
= status
;
321 new_pid
->next
= *listp
;
326 pull_pid_from_list (struct simple_pid_list
**listp
, int pid
, int *statusp
)
328 struct simple_pid_list
**p
;
330 for (p
= listp
; *p
!= NULL
; p
= &(*p
)->next
)
331 if ((*p
)->pid
== pid
)
333 struct simple_pid_list
*next
= (*p
)->next
;
335 *statusp
= (*p
)->status
;
343 /* Return the ptrace options that we want to try to enable. */
346 linux_nat_ptrace_options (int attached
)
351 options
|= PTRACE_O_EXITKILL
;
353 options
|= (PTRACE_O_TRACESYSGOOD
354 | PTRACE_O_TRACEVFORKDONE
355 | PTRACE_O_TRACEVFORK
357 | PTRACE_O_TRACEEXEC
);
362 /* Initialize ptrace and procfs warnings and check for supported
363 ptrace features given PID.
365 ATTACHED should be nonzero iff we attached to the inferior. */
368 linux_init_ptrace_procfs (pid_t pid
, int attached
)
370 int options
= linux_nat_ptrace_options (attached
);
372 linux_enable_event_reporting (pid
, options
);
373 linux_ptrace_init_warnings ();
374 linux_proc_init_warnings ();
377 linux_nat_target::~linux_nat_target ()
381 linux_nat_target::post_attach (int pid
)
383 linux_init_ptrace_procfs (pid
, 1);
386 /* Implement the virtual inf_ptrace_target::post_startup_inferior method. */
389 linux_nat_target::post_startup_inferior (ptid_t ptid
)
391 linux_init_ptrace_procfs (ptid
.pid (), 0);
394 /* Return the number of known LWPs in the tgid given by PID. */
401 for (const lwp_info
*lp ATTRIBUTE_UNUSED
: all_lwps ())
402 if (lp
->ptid
.pid () == pid
)
408 /* Deleter for lwp_info unique_ptr specialisation. */
412 void operator() (struct lwp_info
*lwp
) const
414 delete_lwp (lwp
->ptid
);
418 /* A unique_ptr specialisation for lwp_info. */
420 typedef std::unique_ptr
<struct lwp_info
, lwp_deleter
> lwp_info_up
;
422 /* Target hook for follow_fork. */
425 linux_nat_target::follow_fork (inferior
*child_inf
, ptid_t child_ptid
,
426 target_waitkind fork_kind
, bool follow_child
,
429 inf_ptrace_target::follow_fork (child_inf
, child_ptid
, fork_kind
,
430 follow_child
, detach_fork
);
434 bool has_vforked
= fork_kind
== TARGET_WAITKIND_VFORKED
;
435 ptid_t parent_ptid
= inferior_ptid
;
436 int parent_pid
= parent_ptid
.lwp ();
437 int child_pid
= child_ptid
.lwp ();
439 /* We're already attached to the parent, by default. */
440 lwp_info
*child_lp
= add_lwp (child_ptid
);
441 child_lp
->stopped
= 1;
442 child_lp
->last_resume_kind
= resume_stop
;
444 /* Detach new forked process? */
447 int child_stop_signal
= 0;
448 bool detach_child
= true;
450 /* Move CHILD_LP into a unique_ptr and clear the source pointer
451 to prevent us doing anything stupid with it. */
452 lwp_info_up
child_lp_ptr (child_lp
);
455 linux_target
->low_prepare_to_resume (child_lp_ptr
.get ());
457 /* When debugging an inferior in an architecture that supports
458 hardware single stepping on a kernel without commit
459 6580807da14c423f0d0a708108e6df6ebc8bc83d, the vfork child
460 process starts with the TIF_SINGLESTEP/X86_EFLAGS_TF bits
461 set if the parent process had them set.
462 To work around this, single step the child process
463 once before detaching to clear the flags. */
465 /* Note that we consult the parent's architecture instead of
466 the child's because there's no inferior for the child at
468 if (!gdbarch_software_single_step_p (target_thread_architecture
473 linux_disable_event_reporting (child_pid
);
474 if (ptrace (PTRACE_SINGLESTEP
, child_pid
, 0, 0) < 0)
475 perror_with_name (_("Couldn't do single step"));
476 if (my_waitpid (child_pid
, &status
, 0) < 0)
477 perror_with_name (_("Couldn't wait vfork process"));
480 detach_child
= WIFSTOPPED (status
);
481 child_stop_signal
= WSTOPSIG (status
);
487 int signo
= child_stop_signal
;
490 && !signal_pass_state (gdb_signal_from_host (signo
)))
492 ptrace (PTRACE_DETACH
, child_pid
, 0, signo
);
494 close_proc_mem_file (child_pid
);
500 lwp_info
*parent_lp
= find_lwp_pid (parent_ptid
);
501 linux_nat_debug_printf ("waiting for VFORK_DONE on %d", parent_pid
);
502 parent_lp
->stopped
= 1;
504 /* We'll handle the VFORK_DONE event like any other
505 event, in target_wait. */
510 struct lwp_info
*child_lp
;
512 child_lp
= add_lwp (child_ptid
);
513 child_lp
->stopped
= 1;
514 child_lp
->last_resume_kind
= resume_stop
;
520 linux_nat_target::insert_fork_catchpoint (int pid
)
526 linux_nat_target::remove_fork_catchpoint (int pid
)
532 linux_nat_target::insert_vfork_catchpoint (int pid
)
538 linux_nat_target::remove_vfork_catchpoint (int pid
)
544 linux_nat_target::insert_exec_catchpoint (int pid
)
550 linux_nat_target::remove_exec_catchpoint (int pid
)
556 linux_nat_target::set_syscall_catchpoint (int pid
, bool needed
, int any_count
,
557 gdb::array_view
<const int> syscall_counts
)
559 /* On GNU/Linux, we ignore the arguments. It means that we only
560 enable the syscall catchpoints, but do not disable them.
562 Also, we do not use the `syscall_counts' information because we do not
563 filter system calls here. We let GDB do the logic for us. */
567 /* List of known LWPs, keyed by LWP PID. This speeds up the common
568 case of mapping a PID returned from the kernel to our corresponding
569 lwp_info data structure. */
570 static htab_t lwp_lwpid_htab
;
572 /* Calculate a hash from a lwp_info's LWP PID. */
575 lwp_info_hash (const void *ap
)
577 const struct lwp_info
*lp
= (struct lwp_info
*) ap
;
578 pid_t pid
= lp
->ptid
.lwp ();
580 return iterative_hash_object (pid
, 0);
583 /* Equality function for the lwp_info hash table. Compares the LWP's
587 lwp_lwpid_htab_eq (const void *a
, const void *b
)
589 const struct lwp_info
*entry
= (const struct lwp_info
*) a
;
590 const struct lwp_info
*element
= (const struct lwp_info
*) b
;
592 return entry
->ptid
.lwp () == element
->ptid
.lwp ();
595 /* Create the lwp_lwpid_htab hash table. */
598 lwp_lwpid_htab_create (void)
600 lwp_lwpid_htab
= htab_create (100, lwp_info_hash
, lwp_lwpid_htab_eq
, NULL
);
603 /* Add LP to the hash table. */
606 lwp_lwpid_htab_add_lwp (struct lwp_info
*lp
)
610 slot
= htab_find_slot (lwp_lwpid_htab
, lp
, INSERT
);
611 gdb_assert (slot
!= NULL
&& *slot
== NULL
);
615 /* Head of doubly-linked list of known LWPs. Sorted by reverse
616 creation order. This order is assumed in some cases. E.g.,
617 reaping status after killing alls lwps of a process: the leader LWP
618 must be reaped last. */
620 static intrusive_list
<lwp_info
> lwp_list
;
622 /* See linux-nat.h. */
627 return lwp_info_range (lwp_list
.begin ());
630 /* See linux-nat.h. */
635 return lwp_info_safe_range (lwp_list
.begin ());
638 /* Add LP to sorted-by-reverse-creation-order doubly-linked list. */
641 lwp_list_add (struct lwp_info
*lp
)
643 lwp_list
.push_front (*lp
);
646 /* Remove LP from sorted-by-reverse-creation-order doubly-linked
650 lwp_list_remove (struct lwp_info
*lp
)
652 /* Remove from sorted-by-creation-order list. */
653 lwp_list
.erase (lwp_list
.iterator_to (*lp
));
658 /* Signal mask for use with sigsuspend in linux_nat_wait, initialized in
659 _initialize_linux_nat. */
660 static sigset_t suspend_mask
;
662 /* Signals to block to make that sigsuspend work. */
663 static sigset_t blocked_mask
;
665 /* SIGCHLD action. */
666 static struct sigaction sigchld_action
;
668 /* Block child signals (SIGCHLD and linux threads signals), and store
669 the previous mask in PREV_MASK. */
672 block_child_signals (sigset_t
*prev_mask
)
674 /* Make sure SIGCHLD is blocked. */
675 if (!sigismember (&blocked_mask
, SIGCHLD
))
676 sigaddset (&blocked_mask
, SIGCHLD
);
678 gdb_sigmask (SIG_BLOCK
, &blocked_mask
, prev_mask
);
681 /* Restore child signals mask, previously returned by
682 block_child_signals. */
685 restore_child_signals_mask (sigset_t
*prev_mask
)
687 gdb_sigmask (SIG_SETMASK
, prev_mask
, NULL
);
690 /* Mask of signals to pass directly to the inferior. */
691 static sigset_t pass_mask
;
693 /* Update signals to pass to the inferior. */
695 linux_nat_target::pass_signals
696 (gdb::array_view
<const unsigned char> pass_signals
)
700 sigemptyset (&pass_mask
);
702 for (signo
= 1; signo
< NSIG
; signo
++)
704 int target_signo
= gdb_signal_from_host (signo
);
705 if (target_signo
< pass_signals
.size () && pass_signals
[target_signo
])
706 sigaddset (&pass_mask
, signo
);
712 /* Prototypes for local functions. */
713 static int stop_wait_callback (struct lwp_info
*lp
);
714 static int resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
);
715 static int check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
);
719 /* Destroy and free LP. */
721 lwp_info::~lwp_info ()
723 /* Let the arch specific bits release arch_lwp_info. */
724 linux_target
->low_delete_thread (this->arch_private
);
727 /* Traversal function for purge_lwp_list. */
730 lwp_lwpid_htab_remove_pid (void **slot
, void *info
)
732 struct lwp_info
*lp
= (struct lwp_info
*) *slot
;
733 int pid
= *(int *) info
;
735 if (lp
->ptid
.pid () == pid
)
737 htab_clear_slot (lwp_lwpid_htab
, slot
);
738 lwp_list_remove (lp
);
745 /* Remove all LWPs belong to PID from the lwp list. */
748 purge_lwp_list (int pid
)
750 htab_traverse_noresize (lwp_lwpid_htab
, lwp_lwpid_htab_remove_pid
, &pid
);
753 /* Add the LWP specified by PTID to the list. PTID is the first LWP
754 in the process. Return a pointer to the structure describing the
757 This differs from add_lwp in that we don't let the arch specific
758 bits know about this new thread. Current clients of this callback
759 take the opportunity to install watchpoints in the new thread, and
760 we shouldn't do that for the first thread. If we're spawning a
761 child ("run"), the thread executes the shell wrapper first, and we
762 shouldn't touch it until it execs the program we want to debug.
763 For "attach", it'd be okay to call the callback, but it's not
764 necessary, because watchpoints can't yet have been inserted into
767 static struct lwp_info
*
768 add_initial_lwp (ptid_t ptid
)
770 gdb_assert (ptid
.lwp_p ());
772 lwp_info
*lp
= new lwp_info (ptid
);
775 /* Add to sorted-by-reverse-creation-order list. */
778 /* Add to keyed-by-pid htab. */
779 lwp_lwpid_htab_add_lwp (lp
);
784 /* Add the LWP specified by PID to the list. Return a pointer to the
785 structure describing the new LWP. The LWP should already be
788 static struct lwp_info
*
789 add_lwp (ptid_t ptid
)
793 lp
= add_initial_lwp (ptid
);
795 /* Let the arch specific bits know about this new thread. Current
796 clients of this callback take the opportunity to install
797 watchpoints in the new thread. We don't do this for the first
798 thread though. See add_initial_lwp. */
799 linux_target
->low_new_thread (lp
);
804 /* Remove the LWP specified by PID from the list. */
807 delete_lwp (ptid_t ptid
)
809 lwp_info
dummy (ptid
);
811 void **slot
= htab_find_slot (lwp_lwpid_htab
, &dummy
, NO_INSERT
);
815 lwp_info
*lp
= *(struct lwp_info
**) slot
;
816 gdb_assert (lp
!= NULL
);
818 htab_clear_slot (lwp_lwpid_htab
, slot
);
820 /* Remove from sorted-by-creation-order list. */
821 lwp_list_remove (lp
);
827 /* Return a pointer to the structure describing the LWP corresponding
828 to PID. If no corresponding LWP could be found, return NULL. */
830 static struct lwp_info
*
831 find_lwp_pid (ptid_t ptid
)
840 lwp_info
dummy (ptid_t (0, lwp
));
841 return (struct lwp_info
*) htab_find (lwp_lwpid_htab
, &dummy
);
844 /* See nat/linux-nat.h. */
847 iterate_over_lwps (ptid_t filter
,
848 gdb::function_view
<iterate_over_lwps_ftype
> callback
)
850 for (lwp_info
*lp
: all_lwps_safe ())
852 if (lp
->ptid
.matches (filter
))
854 if (callback (lp
) != 0)
862 /* Update our internal state when changing from one checkpoint to
863 another indicated by NEW_PTID. We can only switch single-threaded
864 applications, so we only create one new LWP, and the previous list
868 linux_nat_switch_fork (ptid_t new_ptid
)
872 purge_lwp_list (inferior_ptid
.pid ());
874 lp
= add_lwp (new_ptid
);
877 /* This changes the thread's ptid while preserving the gdb thread
878 num. Also changes the inferior pid, while preserving the
880 thread_change_ptid (linux_target
, inferior_ptid
, new_ptid
);
882 /* We've just told GDB core that the thread changed target id, but,
883 in fact, it really is a different thread, with different register
885 registers_changed ();
888 /* Handle the exit of a single thread LP. */
891 exit_lwp (struct lwp_info
*lp
)
893 struct thread_info
*th
= find_thread_ptid (linux_target
, lp
->ptid
);
897 if (print_thread_events
)
898 gdb_printf (_("[%s exited]\n"),
899 target_pid_to_str (lp
->ptid
).c_str ());
904 delete_lwp (lp
->ptid
);
907 /* Wait for the LWP specified by LP, which we have just attached to.
908 Returns a wait status for that LWP, to cache. */
911 linux_nat_post_attach_wait (ptid_t ptid
, int *signalled
)
913 pid_t new_pid
, pid
= ptid
.lwp ();
916 if (linux_proc_pid_is_stopped (pid
))
918 linux_nat_debug_printf ("Attaching to a stopped process");
920 /* The process is definitely stopped. It is in a job control
921 stop, unless the kernel predates the TASK_STOPPED /
922 TASK_TRACED distinction, in which case it might be in a
923 ptrace stop. Make sure it is in a ptrace stop; from there we
924 can kill it, signal it, et cetera.
926 First make sure there is a pending SIGSTOP. Since we are
927 already attached, the process can not transition from stopped
928 to running without a PTRACE_CONT; so we know this signal will
929 go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
930 probably already in the queue (unless this kernel is old
931 enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP
932 is not an RT signal, it can only be queued once. */
933 kill_lwp (pid
, SIGSTOP
);
935 /* Finally, resume the stopped process. This will deliver the SIGSTOP
936 (or a higher priority signal, just like normal PTRACE_ATTACH). */
937 ptrace (PTRACE_CONT
, pid
, 0, 0);
940 /* Make sure the initial process is stopped. The user-level threads
941 layer might want to poke around in the inferior, and that won't
942 work if things haven't stabilized yet. */
943 new_pid
= my_waitpid (pid
, &status
, __WALL
);
944 gdb_assert (pid
== new_pid
);
946 if (!WIFSTOPPED (status
))
948 /* The pid we tried to attach has apparently just exited. */
949 linux_nat_debug_printf ("Failed to stop %d: %s", pid
,
950 status_to_str (status
).c_str ());
954 if (WSTOPSIG (status
) != SIGSTOP
)
957 linux_nat_debug_printf ("Received %s after attaching",
958 status_to_str (status
).c_str ());
965 linux_nat_target::create_inferior (const char *exec_file
,
966 const std::string
&allargs
,
967 char **env
, int from_tty
)
969 maybe_disable_address_space_randomization restore_personality
970 (disable_randomization
);
972 /* The fork_child mechanism is synchronous and calls target_wait, so
973 we have to mask the async mode. */
975 /* Make sure we report all signals during startup. */
978 inf_ptrace_target::create_inferior (exec_file
, allargs
, env
, from_tty
);
980 open_proc_mem_file (inferior_ptid
);
983 /* Callback for linux_proc_attach_tgid_threads. Attach to PTID if not
984 already attached. Returns true if a new LWP is found, false
988 attach_proc_task_lwp_callback (ptid_t ptid
)
992 /* Ignore LWPs we're already attached to. */
993 lp
= find_lwp_pid (ptid
);
996 int lwpid
= ptid
.lwp ();
998 if (ptrace (PTRACE_ATTACH
, lwpid
, 0, 0) < 0)
1002 /* Be quiet if we simply raced with the thread exiting.
1003 EPERM is returned if the thread's task still exists, and
1004 is marked as exited or zombie, as well as other
1005 conditions, so in that case, confirm the status in
1006 /proc/PID/status. */
1008 || (err
== EPERM
&& linux_proc_pid_is_gone (lwpid
)))
1010 linux_nat_debug_printf
1011 ("Cannot attach to lwp %d: thread is gone (%d: %s)",
1012 lwpid
, err
, safe_strerror (err
));
1018 = linux_ptrace_attach_fail_reason_string (ptid
, err
);
1020 warning (_("Cannot attach to lwp %d: %s"),
1021 lwpid
, reason
.c_str ());
1026 linux_nat_debug_printf ("PTRACE_ATTACH %s, 0, 0 (OK)",
1027 ptid
.to_string ().c_str ());
1029 lp
= add_lwp (ptid
);
1031 /* The next time we wait for this LWP we'll see a SIGSTOP as
1032 PTRACE_ATTACH brings it to a halt. */
1035 /* We need to wait for a stop before being able to make the
1036 next ptrace call on this LWP. */
1037 lp
->must_set_ptrace_flags
= 1;
1039 /* So that wait collects the SIGSTOP. */
1042 /* Also add the LWP to gdb's thread list, in case a
1043 matching libthread_db is not found (or the process uses
1045 add_thread (linux_target
, lp
->ptid
);
1046 set_running (linux_target
, lp
->ptid
, true);
1047 set_executing (linux_target
, lp
->ptid
, true);
1056 linux_nat_target::attach (const char *args
, int from_tty
)
1058 struct lwp_info
*lp
;
1062 /* Make sure we report all signals during attach. */
1067 inf_ptrace_target::attach (args
, from_tty
);
1069 catch (const gdb_exception_error
&ex
)
1071 pid_t pid
= parse_pid_to_attach (args
);
1072 std::string reason
= linux_ptrace_attach_fail_reason (pid
);
1074 if (!reason
.empty ())
1075 throw_error (ex
.error
, "warning: %s\n%s", reason
.c_str (),
1078 throw_error (ex
.error
, "%s", ex
.what ());
1081 /* The ptrace base target adds the main thread with (pid,0,0)
1082 format. Decorate it with lwp info. */
1083 ptid
= ptid_t (inferior_ptid
.pid (),
1084 inferior_ptid
.pid ());
1085 thread_change_ptid (linux_target
, inferior_ptid
, ptid
);
1087 /* Add the initial process as the first LWP to the list. */
1088 lp
= add_initial_lwp (ptid
);
1090 status
= linux_nat_post_attach_wait (lp
->ptid
, &lp
->signalled
);
1091 if (!WIFSTOPPED (status
))
1093 if (WIFEXITED (status
))
1095 int exit_code
= WEXITSTATUS (status
);
1097 target_terminal::ours ();
1098 target_mourn_inferior (inferior_ptid
);
1100 error (_("Unable to attach: program exited normally."));
1102 error (_("Unable to attach: program exited with code %d."),
1105 else if (WIFSIGNALED (status
))
1107 enum gdb_signal signo
;
1109 target_terminal::ours ();
1110 target_mourn_inferior (inferior_ptid
);
1112 signo
= gdb_signal_from_host (WTERMSIG (status
));
1113 error (_("Unable to attach: program terminated with signal "
1115 gdb_signal_to_name (signo
),
1116 gdb_signal_to_string (signo
));
1119 internal_error (_("unexpected status %d for PID %ld"),
1120 status
, (long) ptid
.lwp ());
1125 open_proc_mem_file (lp
->ptid
);
1127 /* Save the wait status to report later. */
1129 linux_nat_debug_printf ("waitpid %ld, saving status %s",
1130 (long) lp
->ptid
.pid (),
1131 status_to_str (status
).c_str ());
1133 lp
->status
= status
;
1135 /* We must attach to every LWP. If /proc is mounted, use that to
1136 find them now. The inferior may be using raw clone instead of
1137 using pthreads. But even if it is using pthreads, thread_db
1138 walks structures in the inferior's address space to find the list
1139 of threads/LWPs, and those structures may well be corrupted.
1140 Note that once thread_db is loaded, we'll still use it to list
1141 threads and associate pthread info with each LWP. */
1142 linux_proc_attach_tgid_threads (lp
->ptid
.pid (),
1143 attach_proc_task_lwp_callback
);
1146 /* Ptrace-detach the thread with pid PID. */
1149 detach_one_pid (int pid
, int signo
)
1151 if (ptrace (PTRACE_DETACH
, pid
, 0, signo
) < 0)
1153 int save_errno
= errno
;
1155 /* We know the thread exists, so ESRCH must mean the lwp is
1156 zombie. This can happen if one of the already-detached
1157 threads exits the whole thread group. In that case we're
1158 still attached, and must reap the lwp. */
1159 if (save_errno
== ESRCH
)
1163 ret
= my_waitpid (pid
, &status
, __WALL
);
1166 warning (_("Couldn't reap LWP %d while detaching: %s"),
1167 pid
, safe_strerror (errno
));
1169 else if (!WIFEXITED (status
) && !WIFSIGNALED (status
))
1171 warning (_("Reaping LWP %d while detaching "
1172 "returned unexpected status 0x%x"),
1177 error (_("Can't detach %d: %s"),
1178 pid
, safe_strerror (save_errno
));
1181 linux_nat_debug_printf ("PTRACE_DETACH (%d, %s, 0) (OK)",
1182 pid
, strsignal (signo
));
1185 /* Get pending signal of THREAD as a host signal number, for detaching
1186 purposes. This is the signal the thread last stopped for, which we
1187 need to deliver to the thread when detaching, otherwise, it'd be
1191 get_detach_signal (struct lwp_info
*lp
)
1193 enum gdb_signal signo
= GDB_SIGNAL_0
;
1195 /* If we paused threads momentarily, we may have stored pending
1196 events in lp->status or lp->waitstatus (see stop_wait_callback),
1197 and GDB core hasn't seen any signal for those threads.
1198 Otherwise, the last signal reported to the core is found in the
1199 thread object's stop_signal.
1201 There's a corner case that isn't handled here at present. Only
1202 if the thread stopped with a TARGET_WAITKIND_STOPPED does
1203 stop_signal make sense as a real signal to pass to the inferior.
1204 Some catchpoint related events, like
1205 TARGET_WAITKIND_(V)FORK|EXEC|SYSCALL, have their stop_signal set
1206 to GDB_SIGNAL_SIGTRAP when the catchpoint triggers. But,
1207 those traps are debug API (ptrace in our case) related and
1208 induced; the inferior wouldn't see them if it wasn't being
1209 traced. Hence, we should never pass them to the inferior, even
1210 when set to pass state. Since this corner case isn't handled by
1211 infrun.c when proceeding with a signal, for consistency, neither
1212 do we handle it here (or elsewhere in the file we check for
1213 signal pass state). Normally SIGTRAP isn't set to pass state, so
1214 this is really a corner case. */
1216 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
1217 signo
= GDB_SIGNAL_0
; /* a pending ptrace event, not a real signal. */
1218 else if (lp
->status
)
1219 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1222 struct thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1224 if (target_is_non_stop_p () && !tp
->executing ())
1226 if (tp
->has_pending_waitstatus ())
1228 /* If the thread has a pending event, and it was stopped with a
1229 signal, use that signal to resume it. If it has a pending
1230 event of another kind, it was not stopped with a signal, so
1231 resume it without a signal. */
1232 if (tp
->pending_waitstatus ().kind () == TARGET_WAITKIND_STOPPED
)
1233 signo
= tp
->pending_waitstatus ().sig ();
1235 signo
= GDB_SIGNAL_0
;
1238 signo
= tp
->stop_signal ();
1240 else if (!target_is_non_stop_p ())
1243 process_stratum_target
*last_target
;
1245 get_last_target_status (&last_target
, &last_ptid
, nullptr);
1247 if (last_target
== linux_target
1248 && lp
->ptid
.lwp () == last_ptid
.lwp ())
1249 signo
= tp
->stop_signal ();
1253 if (signo
== GDB_SIGNAL_0
)
1255 linux_nat_debug_printf ("lwp %s has no pending signal",
1256 lp
->ptid
.to_string ().c_str ());
1258 else if (!signal_pass_state (signo
))
1260 linux_nat_debug_printf
1261 ("lwp %s had signal %s but it is in no pass state",
1262 lp
->ptid
.to_string ().c_str (), gdb_signal_to_string (signo
));
1266 linux_nat_debug_printf ("lwp %s has pending signal %s",
1267 lp
->ptid
.to_string ().c_str (),
1268 gdb_signal_to_string (signo
));
1270 return gdb_signal_to_host (signo
);
1276 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1277 signal number that should be passed to the LWP when detaching.
1278 Otherwise pass any pending signal the LWP may have, if any. */
1281 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1283 int lwpid
= lp
->ptid
.lwp ();
1286 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
1288 /* If the lwp/thread we are about to detach has a pending fork event,
1289 there is a process GDB is attached to that the core of GDB doesn't know
1290 about. Detach from it. */
1292 /* Check in lwp_info::status. */
1293 if (WIFSTOPPED (lp
->status
) && linux_is_extended_waitstatus (lp
->status
))
1295 int event
= linux_ptrace_get_extended_event (lp
->status
);
1297 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1299 unsigned long child_pid
;
1300 int ret
= ptrace (PTRACE_GETEVENTMSG
, lp
->ptid
.lwp (), 0, &child_pid
);
1302 detach_one_pid (child_pid
, 0);
1304 perror_warning_with_name (_("Failed to detach fork child"));
1308 /* Check in lwp_info::waitstatus. */
1309 if (lp
->waitstatus
.kind () == TARGET_WAITKIND_VFORKED
1310 || lp
->waitstatus
.kind () == TARGET_WAITKIND_FORKED
)
1311 detach_one_pid (lp
->waitstatus
.child_ptid ().pid (), 0);
1314 /* Check in thread_info::pending_waitstatus. */
1315 thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1316 if (tp
->has_pending_waitstatus ())
1318 const target_waitstatus
&ws
= tp
->pending_waitstatus ();
1320 if (ws
.kind () == TARGET_WAITKIND_VFORKED
1321 || ws
.kind () == TARGET_WAITKIND_FORKED
)
1322 detach_one_pid (ws
.child_ptid ().pid (), 0);
1325 /* Check in thread_info::pending_follow. */
1326 if (tp
->pending_follow
.kind () == TARGET_WAITKIND_VFORKED
1327 || tp
->pending_follow
.kind () == TARGET_WAITKIND_FORKED
)
1328 detach_one_pid (tp
->pending_follow
.child_ptid ().pid (), 0);
1330 if (lp
->status
!= 0)
1331 linux_nat_debug_printf ("Pending %s for %s on detach.",
1332 strsignal (WSTOPSIG (lp
->status
)),
1333 lp
->ptid
.to_string ().c_str ());
1335 /* If there is a pending SIGSTOP, get rid of it. */
1338 linux_nat_debug_printf ("Sending SIGCONT to %s",
1339 lp
->ptid
.to_string ().c_str ());
1341 kill_lwp (lwpid
, SIGCONT
);
1345 if (signo_p
== NULL
)
1347 /* Pass on any pending signal for this LWP. */
1348 signo
= get_detach_signal (lp
);
1353 /* Preparing to resume may try to write registers, and fail if the
1354 lwp is zombie. If that happens, ignore the error. We'll handle
1355 it below, when detach fails with ESRCH. */
1358 linux_target
->low_prepare_to_resume (lp
);
1360 catch (const gdb_exception_error
&ex
)
1362 if (!check_ptrace_stopped_lwp_gone (lp
))
1366 detach_one_pid (lwpid
, signo
);
1368 delete_lwp (lp
->ptid
);
1372 detach_callback (struct lwp_info
*lp
)
1374 /* We don't actually detach from the thread group leader just yet.
1375 If the thread group exits, we must reap the zombie clone lwps
1376 before we're able to reap the leader. */
1377 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1378 detach_one_lwp (lp
, NULL
);
1383 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1385 struct lwp_info
*main_lwp
;
1388 /* Don't unregister from the event loop, as there may be other
1389 inferiors running. */
1391 /* Stop all threads before detaching. ptrace requires that the
1392 thread is stopped to successfully detach. */
1393 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1394 /* ... and wait until all of them have reported back that
1395 they're no longer running. */
1396 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1398 /* We can now safely remove breakpoints. We don't this in earlier
1399 in common code because this target doesn't currently support
1400 writing memory while the inferior is running. */
1401 remove_breakpoints_inf (current_inferior ());
1403 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1405 /* Only the initial process should be left right now. */
1406 gdb_assert (num_lwps (pid
) == 1);
1408 main_lwp
= find_lwp_pid (ptid_t (pid
));
1410 if (forks_exist_p ())
1412 /* Multi-fork case. The current inferior_ptid is being detached
1413 from, but there are other viable forks to debug. Detach from
1414 the current fork, and context-switch to the first
1416 linux_fork_detach (from_tty
);
1420 target_announce_detach (from_tty
);
1422 /* Pass on any pending signal for the last LWP. */
1423 int signo
= get_detach_signal (main_lwp
);
1425 detach_one_lwp (main_lwp
, &signo
);
1427 detach_success (inf
);
1430 close_proc_mem_file (pid
);
1433 /* Resume execution of the inferior process. If STEP is nonzero,
1434 single-step it. If SIGNAL is nonzero, give it that signal. */
1437 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1438 enum gdb_signal signo
)
1442 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1443 We only presently need that if the LWP is stepped though (to
1444 handle the case of stepping a breakpoint instruction). */
1447 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1449 lp
->stop_pc
= regcache_read_pc (regcache
);
1454 linux_target
->low_prepare_to_resume (lp
);
1455 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1457 /* Successfully resumed. Clear state that no longer makes sense,
1458 and mark the LWP as running. Must not do this before resuming
1459 otherwise if that fails other code will be confused. E.g., we'd
1460 later try to stop the LWP and hang forever waiting for a stop
1461 status. Note that we must not throw after this is cleared,
1462 otherwise handle_zombie_lwp_error would get confused. */
1465 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1466 registers_changed_ptid (linux_target
, lp
->ptid
);
1469 /* Called when we try to resume a stopped LWP and that errors out. If
1470 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1471 or about to become), discard the error, clear any pending status
1472 the LWP may have, and return true (we'll collect the exit status
1473 soon enough). Otherwise, return false. */
1476 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1478 /* If we get an error after resuming the LWP successfully, we'd
1479 confuse !T state for the LWP being gone. */
1480 gdb_assert (lp
->stopped
);
1482 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1483 because even if ptrace failed with ESRCH, the tracee may be "not
1484 yet fully dead", but already refusing ptrace requests. In that
1485 case the tracee has 'R (Running)' state for a little bit
1486 (observed in Linux 3.18). See also the note on ESRCH in the
1487 ptrace(2) man page. Instead, check whether the LWP has any state
1488 other than ptrace-stopped. */
1490 /* Don't assume anything if /proc/PID/status can't be read. */
1491 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1493 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1495 lp
->waitstatus
.set_ignore ();
1501 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1502 disappears while we try to resume it. */
1505 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1509 linux_resume_one_lwp_throw (lp
, step
, signo
);
1511 catch (const gdb_exception_error
&ex
)
1513 if (!check_ptrace_stopped_lwp_gone (lp
))
1521 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1525 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1527 if (inf
->vfork_child
!= NULL
)
1529 linux_nat_debug_printf ("Not resuming %s (vfork parent)",
1530 lp
->ptid
.to_string ().c_str ());
1532 else if (!lwp_status_pending_p (lp
))
1534 linux_nat_debug_printf ("Resuming sibling %s, %s, %s",
1535 lp
->ptid
.to_string ().c_str (),
1536 (signo
!= GDB_SIGNAL_0
1537 ? strsignal (gdb_signal_to_host (signo
))
1539 step
? "step" : "resume");
1541 linux_resume_one_lwp (lp
, step
, signo
);
1545 linux_nat_debug_printf ("Not resuming sibling %s (has pending)",
1546 lp
->ptid
.to_string ().c_str ());
1550 linux_nat_debug_printf ("Not resuming sibling %s (not stopped)",
1551 lp
->ptid
.to_string ().c_str ());
1554 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1555 Resume LWP with the last stop signal, if it is in pass state. */
1558 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1560 enum gdb_signal signo
= GDB_SIGNAL_0
;
1567 struct thread_info
*thread
;
1569 thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1572 signo
= thread
->stop_signal ();
1573 thread
->set_stop_signal (GDB_SIGNAL_0
);
1577 resume_lwp (lp
, 0, signo
);
1582 resume_clear_callback (struct lwp_info
*lp
)
1585 lp
->last_resume_kind
= resume_stop
;
1590 resume_set_callback (struct lwp_info
*lp
)
1593 lp
->last_resume_kind
= resume_continue
;
1598 linux_nat_target::resume (ptid_t scope_ptid
, int step
, enum gdb_signal signo
)
1600 struct lwp_info
*lp
;
1602 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1603 step
? "step" : "resume",
1604 scope_ptid
.to_string ().c_str (),
1605 (signo
!= GDB_SIGNAL_0
1606 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1607 inferior_ptid
.to_string ().c_str ());
1609 /* Mark the lwps we're resuming as resumed and update their
1610 last_resume_kind to resume_continue. */
1611 iterate_over_lwps (scope_ptid
, resume_set_callback
);
1613 lp
= find_lwp_pid (inferior_ptid
);
1614 gdb_assert (lp
!= NULL
);
1616 /* Remember if we're stepping. */
1617 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1619 /* If we have a pending wait status for this thread, there is no
1620 point in resuming the process. But first make sure that
1621 linux_nat_wait won't preemptively handle the event - we
1622 should never take this short-circuit if we are going to
1623 leave LP running, since we have skipped resuming all the
1624 other threads. This bit of code needs to be synchronized
1625 with linux_nat_wait. */
1627 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1630 && WSTOPSIG (lp
->status
)
1631 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1633 linux_nat_debug_printf
1634 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1636 /* FIXME: What should we do if we are supposed to continue
1637 this thread with a signal? */
1638 gdb_assert (signo
== GDB_SIGNAL_0
);
1639 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1644 if (lwp_status_pending_p (lp
))
1646 /* FIXME: What should we do if we are supposed to continue
1647 this thread with a signal? */
1648 gdb_assert (signo
== GDB_SIGNAL_0
);
1650 linux_nat_debug_printf ("Short circuiting for status 0x%x",
1653 if (target_can_async_p ())
1655 target_async (true);
1656 /* Tell the event loop we have something to process. */
1662 /* No use iterating unless we're resuming other threads. */
1663 if (scope_ptid
!= lp
->ptid
)
1664 iterate_over_lwps (scope_ptid
, [=] (struct lwp_info
*info
)
1666 return linux_nat_resume_callback (info
, lp
);
1669 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1670 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1671 lp
->ptid
.to_string ().c_str (),
1672 (signo
!= GDB_SIGNAL_0
1673 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1675 linux_resume_one_lwp (lp
, step
, signo
);
1678 /* Send a signal to an LWP. */
1681 kill_lwp (int lwpid
, int signo
)
1686 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1687 if (errno
== ENOSYS
)
1689 /* If tkill fails, then we are not using nptl threads, a
1690 configuration we no longer support. */
1691 perror_with_name (("tkill"));
1696 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1697 event, check if the core is interested in it: if not, ignore the
1698 event, and keep waiting; otherwise, we need to toggle the LWP's
1699 syscall entry/exit status, since the ptrace event itself doesn't
1700 indicate it, and report the trap to higher layers. */
1703 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1705 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1706 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1707 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1708 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1712 /* If we're stopping threads, there's a SIGSTOP pending, which
1713 makes it so that the LWP reports an immediate syscall return,
1714 followed by the SIGSTOP. Skip seeing that "return" using
1715 PTRACE_CONT directly, and let stop_wait_callback collect the
1716 SIGSTOP. Later when the thread is resumed, a new syscall
1717 entry event. If we didn't do this (and returned 0), we'd
1718 leave a syscall entry pending, and our caller, by using
1719 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1720 itself. Later, when the user re-resumes this LWP, we'd see
1721 another syscall entry event and we'd mistake it for a return.
1723 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1724 (leaving immediately with LWP->signalled set, without issuing
1725 a PTRACE_CONT), it would still be problematic to leave this
1726 syscall enter pending, as later when the thread is resumed,
1727 it would then see the same syscall exit mentioned above,
1728 followed by the delayed SIGSTOP, while the syscall didn't
1729 actually get to execute. It seems it would be even more
1730 confusing to the user. */
1732 linux_nat_debug_printf
1733 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1734 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1736 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1737 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1742 /* Always update the entry/return state, even if this particular
1743 syscall isn't interesting to the core now. In async mode,
1744 the user could install a new catchpoint for this syscall
1745 between syscall enter/return, and we'll need to know to
1746 report a syscall return if that happens. */
1747 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1748 ? TARGET_WAITKIND_SYSCALL_RETURN
1749 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1751 if (catch_syscall_enabled ())
1753 if (catching_syscall_number (syscall_number
))
1755 /* Alright, an event to report. */
1756 if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
)
1757 ourstatus
->set_syscall_entry (syscall_number
);
1758 else if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_RETURN
)
1759 ourstatus
->set_syscall_return (syscall_number
);
1761 gdb_assert_not_reached ("unexpected syscall state");
1763 linux_nat_debug_printf
1764 ("stopping for %s of syscall %d for LWP %ld",
1765 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1766 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1771 linux_nat_debug_printf
1772 ("ignoring %s of syscall %d for LWP %ld",
1773 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1774 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1778 /* If we had been syscall tracing, and hence used PT_SYSCALL
1779 before on this LWP, it could happen that the user removes all
1780 syscall catchpoints before we get to process this event.
1781 There are two noteworthy issues here:
1783 - When stopped at a syscall entry event, resuming with
1784 PT_STEP still resumes executing the syscall and reports a
1787 - Only PT_SYSCALL catches syscall enters. If we last
1788 single-stepped this thread, then this event can't be a
1789 syscall enter. If we last single-stepped this thread, this
1790 has to be a syscall exit.
1792 The points above mean that the next resume, be it PT_STEP or
1793 PT_CONTINUE, can not trigger a syscall trace event. */
1794 linux_nat_debug_printf
1795 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1796 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1797 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1800 /* The core isn't interested in this event. For efficiency, avoid
1801 stopping all threads only to have the core resume them all again.
1802 Since we're not stopping threads, if we're still syscall tracing
1803 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1804 subsequent syscall. Simply resume using the inf-ptrace layer,
1805 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1807 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1811 /* Handle a GNU/Linux extended wait response. If we see a clone
1812 event, we need to add the new LWP to our list (and not report the
1813 trap to higher layers). This function returns non-zero if the
1814 event should be ignored and we should wait again. If STOPPING is
1815 true, the new LWP remains stopped, otherwise it is continued. */
1818 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1820 int pid
= lp
->ptid
.lwp ();
1821 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1822 int event
= linux_ptrace_get_extended_event (status
);
1824 /* All extended events we currently use are mid-syscall. Only
1825 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1826 you have to be using PTRACE_SEIZE to get that. */
1827 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1829 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1830 || event
== PTRACE_EVENT_CLONE
)
1832 unsigned long new_pid
;
1835 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1837 /* If we haven't already seen the new PID stop, wait for it now. */
1838 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1840 /* The new child has a pending SIGSTOP. We can't affect it until it
1841 hits the SIGSTOP, but we're already attached. */
1842 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1844 perror_with_name (_("waiting for new child"));
1845 else if (ret
!= new_pid
)
1846 internal_error (_("wait returned unexpected PID %d"), ret
);
1847 else if (!WIFSTOPPED (status
))
1848 internal_error (_("wait returned unexpected status 0x%x"), status
);
1851 ptid_t
child_ptid (new_pid
, new_pid
);
1853 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1855 open_proc_mem_file (child_ptid
);
1857 /* The arch-specific native code may need to know about new
1858 forks even if those end up never mapped to an
1860 linux_target
->low_new_fork (lp
, new_pid
);
1862 else if (event
== PTRACE_EVENT_CLONE
)
1864 linux_target
->low_new_clone (lp
, new_pid
);
1867 if (event
== PTRACE_EVENT_FORK
1868 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1870 /* Handle checkpointing by linux-fork.c here as a special
1871 case. We don't want the follow-fork-mode or 'catch fork'
1872 to interfere with this. */
1874 /* This won't actually modify the breakpoint list, but will
1875 physically remove the breakpoints from the child. */
1876 detach_breakpoints (ptid_t (new_pid
, new_pid
));
1878 /* Retain child fork in ptrace (stopped) state. */
1879 if (!find_fork_pid (new_pid
))
1882 /* Report as spurious, so that infrun doesn't want to follow
1883 this fork. We're actually doing an infcall in
1885 ourstatus
->set_spurious ();
1887 /* Report the stop to the core. */
1891 if (event
== PTRACE_EVENT_FORK
)
1892 ourstatus
->set_forked (child_ptid
);
1893 else if (event
== PTRACE_EVENT_VFORK
)
1894 ourstatus
->set_vforked (child_ptid
);
1895 else if (event
== PTRACE_EVENT_CLONE
)
1897 struct lwp_info
*new_lp
;
1899 ourstatus
->set_ignore ();
1901 linux_nat_debug_printf
1902 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
1904 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
));
1905 new_lp
->stopped
= 1;
1906 new_lp
->resumed
= 1;
1908 /* If the thread_db layer is active, let it record the user
1909 level thread id and status, and add the thread to GDB's
1911 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
1913 /* The process is not using thread_db. Add the LWP to
1915 target_post_attach (new_lp
->ptid
.lwp ());
1916 add_thread (linux_target
, new_lp
->ptid
);
1919 /* Even if we're stopping the thread for some reason
1920 internal to this module, from the perspective of infrun
1921 and the user/frontend, this new thread is running until
1922 it next reports a stop. */
1923 set_running (linux_target
, new_lp
->ptid
, true);
1924 set_executing (linux_target
, new_lp
->ptid
, true);
1926 if (WSTOPSIG (status
) != SIGSTOP
)
1928 /* This can happen if someone starts sending signals to
1929 the new thread before it gets a chance to run, which
1930 have a lower number than SIGSTOP (e.g. SIGUSR1).
1931 This is an unlikely case, and harder to handle for
1932 fork / vfork than for clone, so we do not try - but
1933 we handle it for clone events here. */
1935 new_lp
->signalled
= 1;
1937 /* We created NEW_LP so it cannot yet contain STATUS. */
1938 gdb_assert (new_lp
->status
== 0);
1940 /* Save the wait status to report later. */
1941 linux_nat_debug_printf
1942 ("waitpid of new LWP %ld, saving status %s",
1943 (long) new_lp
->ptid
.lwp (), status_to_str (status
).c_str ());
1944 new_lp
->status
= status
;
1946 else if (report_thread_events
)
1948 new_lp
->waitstatus
.set_thread_created ();
1949 new_lp
->status
= status
;
1958 if (event
== PTRACE_EVENT_EXEC
)
1960 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
1962 /* Close the previous /proc/PID/mem file for this inferior,
1963 which was using the address space which is now gone.
1964 Reading/writing from this file would return 0/EOF. */
1965 close_proc_mem_file (lp
->ptid
.pid ());
1967 /* Open a new file for the new address space. */
1968 open_proc_mem_file (lp
->ptid
);
1970 ourstatus
->set_execd
1971 (make_unique_xstrdup (linux_proc_pid_to_exec_file (pid
)));
1973 /* The thread that execed must have been resumed, but, when a
1974 thread execs, it changes its tid to the tgid, and the old
1975 tgid thread might have not been resumed. */
1980 if (event
== PTRACE_EVENT_VFORK_DONE
)
1982 linux_nat_debug_printf
1983 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld",
1985 ourstatus
->set_vfork_done ();
1989 internal_error (_("unknown ptrace event %d"), event
);
1992 /* Suspend waiting for a signal. We're mostly interested in
1998 linux_nat_debug_printf ("about to sigsuspend");
1999 sigsuspend (&suspend_mask
);
2001 /* If the quit flag is set, it means that the user pressed Ctrl-C
2002 and we're debugging a process that is running on a separate
2003 terminal, so we must forward the Ctrl-C to the inferior. (If the
2004 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2005 inferior directly.) We must do this here because functions that
2006 need to block waiting for a signal loop forever until there's an
2007 event to report before returning back to the event loop. */
2008 if (!target_terminal::is_ours ())
2010 if (check_quit_flag ())
2011 target_pass_ctrlc ();
2015 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2019 wait_lwp (struct lwp_info
*lp
)
2023 int thread_dead
= 0;
2026 gdb_assert (!lp
->stopped
);
2027 gdb_assert (lp
->status
== 0);
2029 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2030 block_child_signals (&prev_mask
);
2034 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2035 if (pid
== -1 && errno
== ECHILD
)
2037 /* The thread has previously exited. We need to delete it
2038 now because if this was a non-leader thread execing, we
2039 won't get an exit event. See comments on exec events at
2040 the top of the file. */
2042 linux_nat_debug_printf ("%s vanished.",
2043 lp
->ptid
.to_string ().c_str ());
2048 /* Bugs 10970, 12702.
2049 Thread group leader may have exited in which case we'll lock up in
2050 waitpid if there are other threads, even if they are all zombies too.
2051 Basically, we're not supposed to use waitpid this way.
2052 tkill(pid,0) cannot be used here as it gets ESRCH for both
2053 for zombie and running processes.
2055 As a workaround, check if we're waiting for the thread group leader and
2056 if it's a zombie, and avoid calling waitpid if it is.
2058 This is racy, what if the tgl becomes a zombie right after we check?
2059 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2060 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2062 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2063 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2066 linux_nat_debug_printf ("Thread group leader %s vanished.",
2067 lp
->ptid
.to_string ().c_str ());
2071 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2072 get invoked despite our caller had them intentionally blocked by
2073 block_child_signals. This is sensitive only to the loop of
2074 linux_nat_wait_1 and there if we get called my_waitpid gets called
2075 again before it gets to sigsuspend so we can safely let the handlers
2076 get executed here. */
2080 restore_child_signals_mask (&prev_mask
);
2084 gdb_assert (pid
== lp
->ptid
.lwp ());
2086 linux_nat_debug_printf ("waitpid %s received %s",
2087 lp
->ptid
.to_string ().c_str (),
2088 status_to_str (status
).c_str ());
2090 /* Check if the thread has exited. */
2091 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2093 if (report_thread_events
2094 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2096 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2098 /* If this is the leader exiting, it means the whole
2099 process is gone. Store the status to report to the
2100 core. Store it in lp->waitstatus, because lp->status
2101 would be ambiguous (W_EXITCODE(0,0) == 0). */
2102 lp
->waitstatus
= host_status_to_waitstatus (status
);
2107 linux_nat_debug_printf ("%s exited.",
2108 lp
->ptid
.to_string ().c_str ());
2118 gdb_assert (WIFSTOPPED (status
));
2121 if (lp
->must_set_ptrace_flags
)
2123 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2124 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2126 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2127 lp
->must_set_ptrace_flags
= 0;
2130 /* Handle GNU/Linux's syscall SIGTRAPs. */
2131 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2133 /* No longer need the sysgood bit. The ptrace event ends up
2134 recorded in lp->waitstatus if we care for it. We can carry
2135 on handling the event like a regular SIGTRAP from here
2137 status
= W_STOPCODE (SIGTRAP
);
2138 if (linux_handle_syscall_trap (lp
, 1))
2139 return wait_lwp (lp
);
2143 /* Almost all other ptrace-stops are known to be outside of system
2144 calls, with further exceptions in linux_handle_extended_wait. */
2145 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2148 /* Handle GNU/Linux's extended waitstatus for trace events. */
2149 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2150 && linux_is_extended_waitstatus (status
))
2152 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2153 linux_handle_extended_wait (lp
, status
);
2160 /* Send a SIGSTOP to LP. */
2163 stop_callback (struct lwp_info
*lp
)
2165 if (!lp
->stopped
&& !lp
->signalled
)
2169 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2170 lp
->ptid
.to_string ().c_str ());
2173 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2174 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2175 errno
? safe_strerror (errno
) : "ERRNO-OK");
2178 gdb_assert (lp
->status
== 0);
2184 /* Request a stop on LWP. */
2187 linux_stop_lwp (struct lwp_info
*lwp
)
2189 stop_callback (lwp
);
2192 /* See linux-nat.h */
2195 linux_stop_and_wait_all_lwps (void)
2197 /* Stop all LWP's ... */
2198 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2200 /* ... and wait until all of them have reported back that
2201 they're no longer running. */
2202 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2205 /* See linux-nat.h */
2208 linux_unstop_all_lwps (void)
2210 iterate_over_lwps (minus_one_ptid
,
2211 [] (struct lwp_info
*info
)
2213 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2217 /* Return non-zero if LWP PID has a pending SIGINT. */
2220 linux_nat_has_pending_sigint (int pid
)
2222 sigset_t pending
, blocked
, ignored
;
2224 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2226 if (sigismember (&pending
, SIGINT
)
2227 && !sigismember (&ignored
, SIGINT
))
2233 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2236 set_ignore_sigint (struct lwp_info
*lp
)
2238 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2239 flag to consume the next one. */
2240 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2241 && WSTOPSIG (lp
->status
) == SIGINT
)
2244 lp
->ignore_sigint
= 1;
2249 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2250 This function is called after we know the LWP has stopped; if the LWP
2251 stopped before the expected SIGINT was delivered, then it will never have
2252 arrived. Also, if the signal was delivered to a shared queue and consumed
2253 by a different thread, it will never be delivered to this LWP. */
2256 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2258 if (!lp
->ignore_sigint
)
2261 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2263 linux_nat_debug_printf ("Clearing bogus flag for %s",
2264 lp
->ptid
.to_string ().c_str ());
2265 lp
->ignore_sigint
= 0;
2269 /* Fetch the possible triggered data watchpoint info and store it in
2272 On some archs, like x86, that use debug registers to set
2273 watchpoints, it's possible that the way to know which watched
2274 address trapped, is to check the register that is used to select
2275 which address to watch. Problem is, between setting the watchpoint
2276 and reading back which data address trapped, the user may change
2277 the set of watchpoints, and, as a consequence, GDB changes the
2278 debug registers in the inferior. To avoid reading back a stale
2279 stopped-data-address when that happens, we cache in LP the fact
2280 that a watchpoint trapped, and the corresponding data address, as
2281 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2282 registers meanwhile, we have the cached data we can rely on. */
2285 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2287 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2288 inferior_ptid
= lp
->ptid
;
2290 if (linux_target
->low_stopped_by_watchpoint ())
2292 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2293 lp
->stopped_data_address_p
2294 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2297 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2300 /* Returns true if the LWP had stopped for a watchpoint. */
2303 linux_nat_target::stopped_by_watchpoint ()
2305 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2307 gdb_assert (lp
!= NULL
);
2309 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2313 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2315 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2317 gdb_assert (lp
!= NULL
);
2319 *addr_p
= lp
->stopped_data_address
;
2321 return lp
->stopped_data_address_p
;
2324 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2327 linux_nat_target::low_status_is_event (int status
)
2329 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2332 /* Wait until LP is stopped. */
2335 stop_wait_callback (struct lwp_info
*lp
)
2337 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2339 /* If this is a vfork parent, bail out, it is not going to report
2340 any SIGSTOP until the vfork is done with. */
2341 if (inf
->vfork_child
!= NULL
)
2348 status
= wait_lwp (lp
);
2352 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2353 && WSTOPSIG (status
) == SIGINT
)
2355 lp
->ignore_sigint
= 0;
2358 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2360 linux_nat_debug_printf
2361 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2362 lp
->ptid
.to_string ().c_str (),
2363 errno
? safe_strerror (errno
) : "OK");
2365 return stop_wait_callback (lp
);
2368 maybe_clear_ignore_sigint (lp
);
2370 if (WSTOPSIG (status
) != SIGSTOP
)
2372 /* The thread was stopped with a signal other than SIGSTOP. */
2374 linux_nat_debug_printf ("Pending event %s in %s",
2375 status_to_str ((int) status
).c_str (),
2376 lp
->ptid
.to_string ().c_str ());
2378 /* Save the sigtrap event. */
2379 lp
->status
= status
;
2380 gdb_assert (lp
->signalled
);
2381 save_stop_reason (lp
);
2385 /* We caught the SIGSTOP that we intended to catch. */
2387 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2388 lp
->ptid
.to_string ().c_str ());
2392 /* If we are waiting for this stop so we can report the thread
2393 stopped then we need to record this status. Otherwise, we can
2394 now discard this stop event. */
2395 if (lp
->last_resume_kind
== resume_stop
)
2397 lp
->status
= status
;
2398 save_stop_reason (lp
);
2406 /* Return non-zero if LP has a wait status pending. Discard the
2407 pending event and resume the LWP if the event that originally
2408 caused the stop became uninteresting. */
2411 status_callback (struct lwp_info
*lp
)
2413 /* Only report a pending wait status if we pretend that this has
2414 indeed been resumed. */
2418 if (!lwp_status_pending_p (lp
))
2421 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2422 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2424 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2428 pc
= regcache_read_pc (regcache
);
2430 if (pc
!= lp
->stop_pc
)
2432 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2433 lp
->ptid
.to_string ().c_str (),
2434 paddress (target_gdbarch (), lp
->stop_pc
),
2435 paddress (target_gdbarch (), pc
));
2439 #if !USE_SIGTRAP_SIGINFO
2440 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2442 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2443 lp
->ptid
.to_string ().c_str (),
2444 paddress (target_gdbarch (), lp
->stop_pc
));
2452 linux_nat_debug_printf ("pending event of %s cancelled.",
2453 lp
->ptid
.to_string ().c_str ());
2456 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2464 /* Count the LWP's that have had events. */
2467 count_events_callback (struct lwp_info
*lp
, int *count
)
2469 gdb_assert (count
!= NULL
);
2471 /* Select only resumed LWPs that have an event pending. */
2472 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2478 /* Select the LWP (if any) that is currently being single-stepped. */
2481 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2483 if (lp
->last_resume_kind
== resume_step
2490 /* Returns true if LP has a status pending. */
2493 lwp_status_pending_p (struct lwp_info
*lp
)
2495 /* We check for lp->waitstatus in addition to lp->status, because we
2496 can have pending process exits recorded in lp->status and
2497 W_EXITCODE(0,0) happens to be 0. */
2498 return lp
->status
!= 0 || lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
;
2501 /* Select the Nth LWP that has had an event. */
2504 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2506 gdb_assert (selector
!= NULL
);
2508 /* Select only resumed LWPs that have an event pending. */
2509 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2510 if ((*selector
)-- == 0)
2516 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2517 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2518 and save the result in the LWP's stop_reason field. If it stopped
2519 for a breakpoint, decrement the PC if necessary on the lwp's
2523 save_stop_reason (struct lwp_info
*lp
)
2525 struct regcache
*regcache
;
2526 struct gdbarch
*gdbarch
;
2529 #if USE_SIGTRAP_SIGINFO
2533 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2534 gdb_assert (lp
->status
!= 0);
2536 if (!linux_target
->low_status_is_event (lp
->status
))
2539 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2540 if (inf
->starting_up
)
2543 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2544 gdbarch
= regcache
->arch ();
2546 pc
= regcache_read_pc (regcache
);
2547 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2549 #if USE_SIGTRAP_SIGINFO
2550 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2552 if (siginfo
.si_signo
== SIGTRAP
)
2554 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2555 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2557 /* The si_code is ambiguous on this arch -- check debug
2559 if (!check_stopped_by_watchpoint (lp
))
2560 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2562 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2564 /* If we determine the LWP stopped for a SW breakpoint,
2565 trust it. Particularly don't check watchpoint
2566 registers, because, at least on s390, we'd find
2567 stopped-by-watchpoint as long as there's a watchpoint
2569 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2571 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2573 /* This can indicate either a hardware breakpoint or
2574 hardware watchpoint. Check debug registers. */
2575 if (!check_stopped_by_watchpoint (lp
))
2576 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2578 else if (siginfo
.si_code
== TRAP_TRACE
)
2580 linux_nat_debug_printf ("%s stopped by trace",
2581 lp
->ptid
.to_string ().c_str ());
2583 /* We may have single stepped an instruction that
2584 triggered a watchpoint. In that case, on some
2585 architectures (such as x86), instead of TRAP_HWBKPT,
2586 si_code indicates TRAP_TRACE, and we need to check
2587 the debug registers separately. */
2588 check_stopped_by_watchpoint (lp
);
2593 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2594 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2597 /* The LWP was either continued, or stepped a software
2598 breakpoint instruction. */
2599 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2602 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2603 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2605 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2606 check_stopped_by_watchpoint (lp
);
2609 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2611 linux_nat_debug_printf ("%s stopped by software breakpoint",
2612 lp
->ptid
.to_string ().c_str ());
2614 /* Back up the PC if necessary. */
2616 regcache_write_pc (regcache
, sw_bp_pc
);
2618 /* Update this so we record the correct stop PC below. */
2621 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2623 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2624 lp
->ptid
.to_string ().c_str ());
2626 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2628 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2629 lp
->ptid
.to_string ().c_str ());
2636 /* Returns true if the LWP had stopped for a software breakpoint. */
2639 linux_nat_target::stopped_by_sw_breakpoint ()
2641 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2643 gdb_assert (lp
!= NULL
);
2645 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2648 /* Implement the supports_stopped_by_sw_breakpoint method. */
2651 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2653 return USE_SIGTRAP_SIGINFO
;
2656 /* Returns true if the LWP had stopped for a hardware
2657 breakpoint/watchpoint. */
2660 linux_nat_target::stopped_by_hw_breakpoint ()
2662 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2664 gdb_assert (lp
!= NULL
);
2666 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2669 /* Implement the supports_stopped_by_hw_breakpoint method. */
2672 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2674 return USE_SIGTRAP_SIGINFO
;
2677 /* Select one LWP out of those that have events pending. */
2680 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2683 int random_selector
;
2684 struct lwp_info
*event_lp
= NULL
;
2686 /* Record the wait status for the original LWP. */
2687 (*orig_lp
)->status
= *status
;
2689 /* In all-stop, give preference to the LWP that is being
2690 single-stepped. There will be at most one, and it will be the
2691 LWP that the core is most interested in. If we didn't do this,
2692 then we'd have to handle pending step SIGTRAPs somehow in case
2693 the core later continues the previously-stepped thread, as
2694 otherwise we'd report the pending SIGTRAP then, and the core, not
2695 having stepped the thread, wouldn't understand what the trap was
2696 for, and therefore would report it to the user as a random
2698 if (!target_is_non_stop_p ())
2700 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2701 if (event_lp
!= NULL
)
2703 linux_nat_debug_printf ("Select single-step %s",
2704 event_lp
->ptid
.to_string ().c_str ());
2708 if (event_lp
== NULL
)
2710 /* Pick one at random, out of those which have had events. */
2712 /* First see how many events we have. */
2713 iterate_over_lwps (filter
,
2714 [&] (struct lwp_info
*info
)
2716 return count_events_callback (info
, &num_events
);
2718 gdb_assert (num_events
> 0);
2720 /* Now randomly pick a LWP out of those that have had
2722 random_selector
= (int)
2723 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2726 linux_nat_debug_printf ("Found %d events, selecting #%d",
2727 num_events
, random_selector
);
2730 = (iterate_over_lwps
2732 [&] (struct lwp_info
*info
)
2734 return select_event_lwp_callback (info
,
2739 if (event_lp
!= NULL
)
2741 /* Switch the event LWP. */
2742 *orig_lp
= event_lp
;
2743 *status
= event_lp
->status
;
2746 /* Flush the wait status for the event LWP. */
2747 (*orig_lp
)->status
= 0;
2750 /* Return non-zero if LP has been resumed. */
2753 resumed_callback (struct lwp_info
*lp
)
2758 /* Check if we should go on and pass this event to common code.
2760 If so, save the status to the lwp_info structure associated to LWPID. */
2763 linux_nat_filter_event (int lwpid
, int status
)
2765 struct lwp_info
*lp
;
2766 int event
= linux_ptrace_get_extended_event (status
);
2768 lp
= find_lwp_pid (ptid_t (lwpid
));
2770 /* Check for events reported by anything not in our LWP list. */
2773 if (WIFSTOPPED (status
))
2775 if (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
)
2777 /* A non-leader thread exec'ed after we've seen the
2778 leader zombie, and removed it from our lists (in
2779 check_zombie_leaders). The non-leader thread changes
2780 its tid to the tgid. */
2781 linux_nat_debug_printf
2782 ("Re-adding thread group leader LWP %d after exec.",
2785 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2788 add_thread (linux_target
, lp
->ptid
);
2792 /* A process we are controlling has forked and the new
2793 child's stop was reported to us by the kernel. Save
2794 its PID and go back to waiting for the fork event to
2795 be reported - the stopped process might be returned
2796 from waitpid before or after the fork event is. */
2797 linux_nat_debug_printf
2798 ("Saving LWP %d status %s in stopped_pids list",
2799 lwpid
, status_to_str (status
).c_str ());
2800 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2805 /* Don't report an event for the exit of an LWP not in our
2806 list, i.e. not part of any inferior we're debugging.
2807 This can happen if we detach from a program we originally
2808 forked and then it exits. However, note that we may have
2809 earlier deleted a leader of an inferior we're debugging,
2810 in check_zombie_leaders. Re-add it back here if so. */
2811 for (inferior
*inf
: all_inferiors (linux_target
))
2813 if (inf
->pid
== lwpid
)
2815 linux_nat_debug_printf
2816 ("Re-adding thread group leader LWP %d after exit.",
2819 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2821 add_thread (linux_target
, lp
->ptid
);
2831 /* This LWP is stopped now. (And if dead, this prevents it from
2832 ever being continued.) */
2835 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2837 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2838 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2840 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2841 lp
->must_set_ptrace_flags
= 0;
2844 /* Handle GNU/Linux's syscall SIGTRAPs. */
2845 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2847 /* No longer need the sysgood bit. The ptrace event ends up
2848 recorded in lp->waitstatus if we care for it. We can carry
2849 on handling the event like a regular SIGTRAP from here
2851 status
= W_STOPCODE (SIGTRAP
);
2852 if (linux_handle_syscall_trap (lp
, 0))
2857 /* Almost all other ptrace-stops are known to be outside of system
2858 calls, with further exceptions in linux_handle_extended_wait. */
2859 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2862 /* Handle GNU/Linux's extended waitstatus for trace events. */
2863 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2864 && linux_is_extended_waitstatus (status
))
2866 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2868 if (linux_handle_extended_wait (lp
, status
))
2872 /* Check if the thread has exited. */
2873 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2875 if (!report_thread_events
&& !is_leader (lp
))
2877 linux_nat_debug_printf ("%s exited.",
2878 lp
->ptid
.to_string ().c_str ());
2880 /* If this was not the leader exiting, then the exit signal
2881 was not the end of the debugged application and should be
2887 /* Note that even if the leader was ptrace-stopped, it can still
2888 exit, if e.g., some other thread brings down the whole
2889 process (calls `exit'). So don't assert that the lwp is
2891 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2892 lp
->ptid
.lwp (), lp
->resumed
);
2894 /* Dead LWP's aren't expected to reported a pending sigstop. */
2897 /* Store the pending event in the waitstatus, because
2898 W_EXITCODE(0,0) == 0. */
2899 lp
->waitstatus
= host_status_to_waitstatus (status
);
2903 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2904 an attempt to stop an LWP. */
2906 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2910 if (lp
->last_resume_kind
== resume_stop
)
2912 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2913 lp
->ptid
.to_string ().c_str ());
2917 /* This is a delayed SIGSTOP. Filter out the event. */
2919 linux_nat_debug_printf
2920 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2921 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2922 lp
->ptid
.to_string ().c_str ());
2924 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2925 gdb_assert (lp
->resumed
);
2930 /* Make sure we don't report a SIGINT that we have already displayed
2931 for another thread. */
2932 if (lp
->ignore_sigint
2933 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2935 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2936 lp
->ptid
.to_string ().c_str ());
2938 /* This is a delayed SIGINT. */
2939 lp
->ignore_sigint
= 0;
2941 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2942 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
2943 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2944 lp
->ptid
.to_string ().c_str ());
2945 gdb_assert (lp
->resumed
);
2947 /* Discard the event. */
2951 /* Don't report signals that GDB isn't interested in, such as
2952 signals that are neither printed nor stopped upon. Stopping all
2953 threads can be a bit time-consuming, so if we want decent
2954 performance with heavily multi-threaded programs, especially when
2955 they're using a high frequency timer, we'd better avoid it if we
2957 if (WIFSTOPPED (status
))
2959 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
2961 if (!target_is_non_stop_p ())
2963 /* Only do the below in all-stop, as we currently use SIGSTOP
2964 to implement target_stop (see linux_nat_stop) in
2966 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
2968 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
2969 forwarded to the entire process group, that is, all LWPs
2970 will receive it - unless they're using CLONE_THREAD to
2971 share signals. Since we only want to report it once, we
2972 mark it as ignored for all LWPs except this one. */
2973 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
2974 lp
->ignore_sigint
= 0;
2977 maybe_clear_ignore_sigint (lp
);
2980 /* When using hardware single-step, we need to report every signal.
2981 Otherwise, signals in pass_mask may be short-circuited
2982 except signals that might be caused by a breakpoint, or SIGSTOP
2983 if we sent the SIGSTOP and are waiting for it to arrive. */
2985 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
2986 && (WSTOPSIG (status
) != SIGSTOP
2987 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
2988 && !linux_wstatus_maybe_breakpoint (status
))
2990 linux_resume_one_lwp (lp
, lp
->step
, signo
);
2991 linux_nat_debug_printf
2992 ("%s %s, %s (preempt 'handle')",
2993 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2994 lp
->ptid
.to_string ().c_str (),
2995 (signo
!= GDB_SIGNAL_0
2996 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3001 /* An interesting event. */
3003 lp
->status
= status
;
3004 save_stop_reason (lp
);
3007 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3008 their exits until all other threads in the group have exited. */
3011 check_zombie_leaders (void)
3013 for (inferior
*inf
: all_inferiors ())
3015 struct lwp_info
*leader_lp
;
3020 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3021 if (leader_lp
!= NULL
3022 /* Check if there are other threads in the group, as we may
3023 have raced with the inferior simply exiting. Note this
3024 isn't a watertight check. If the inferior is
3025 multi-threaded and is exiting, it may be we see the
3026 leader as zombie before we reap all the non-leader
3027 threads. See comments below. */
3028 && num_lwps (inf
->pid
) > 1
3029 && linux_proc_pid_is_zombie (inf
->pid
))
3031 /* A zombie leader in a multi-threaded program can mean one
3034 #1 - Only the leader exited, not the whole program, e.g.,
3035 with pthread_exit. Since we can't reap the leader's exit
3036 status until all other threads are gone and reaped too,
3037 we want to delete the zombie leader right away, as it
3038 can't be debugged, we can't read its registers, etc.
3039 This is the main reason we check for zombie leaders
3042 #2 - The whole thread-group/process exited (a group exit,
3043 via e.g. exit(3), and there is (or will be shortly) an
3044 exit reported for each thread in the process, and then
3045 finally an exit for the leader once the non-leaders are
3048 #3 - There are 3 or more threads in the group, and a
3049 thread other than the leader exec'd. See comments on
3050 exec events at the top of the file.
3052 Ideally we would never delete the leader for case #2.
3053 Instead, we want to collect the exit status of each
3054 non-leader thread, and then finally collect the exit
3055 status of the leader as normal and use its exit code as
3056 whole-process exit code. Unfortunately, there's no
3057 race-free way to distinguish cases #1 and #2. We can't
3058 assume the exit events for the non-leaders threads are
3059 already pending in the kernel, nor can we assume the
3060 non-leader threads are in zombie state already. Between
3061 the leader becoming zombie and the non-leaders exiting
3062 and becoming zombie themselves, there's a small time
3063 window, so such a check would be racy. Temporarily
3064 pausing all threads and checking to see if all threads
3065 exit or not before re-resuming them would work in the
3066 case that all threads are running right now, but it
3067 wouldn't work if some thread is currently already
3068 ptrace-stopped, e.g., due to scheduler-locking.
3070 So what we do is we delete the leader anyhow, and then
3071 later on when we see its exit status, we re-add it back.
3072 We also make sure that we only report a whole-process
3073 exit when we see the leader exiting, as opposed to when
3074 the last LWP in the LWP list exits, which can be a
3075 non-leader if we deleted the leader here. */
3076 linux_nat_debug_printf ("Thread group leader %d zombie "
3077 "(it exited, or another thread execd), "
3080 exit_lwp (leader_lp
);
3085 /* Convenience function that is called when the kernel reports an exit
3086 event. This decides whether to report the event to GDB as a
3087 process exit event, a thread exit event, or to suppress the
3091 filter_exit_event (struct lwp_info
*event_child
,
3092 struct target_waitstatus
*ourstatus
)
3094 ptid_t ptid
= event_child
->ptid
;
3096 if (!is_leader (event_child
))
3098 if (report_thread_events
)
3099 ourstatus
->set_thread_exited (0);
3101 ourstatus
->set_ignore ();
3103 exit_lwp (event_child
);
3110 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3111 target_wait_flags target_options
)
3114 enum resume_kind last_resume_kind
;
3115 struct lwp_info
*lp
;
3118 linux_nat_debug_printf ("enter");
3120 /* The first time we get here after starting a new inferior, we may
3121 not have added it to the LWP list yet - this is the earliest
3122 moment at which we know its PID. */
3123 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3125 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3127 /* Upgrade the main thread's ptid. */
3128 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3129 lp
= add_initial_lwp (lwp_ptid
);
3133 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3134 block_child_signals (&prev_mask
);
3136 /* First check if there is a LWP with a wait status pending. */
3137 lp
= iterate_over_lwps (ptid
, status_callback
);
3140 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3141 status_to_str (lp
->status
).c_str (),
3142 lp
->ptid
.to_string ().c_str ());
3145 /* But if we don't find a pending event, we'll have to wait. Always
3146 pull all events out of the kernel. We'll randomly select an
3147 event LWP out of all that have events, to prevent starvation. */
3153 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3156 - If the thread group leader exits while other threads in the
3157 thread group still exist, waitpid(TGID, ...) hangs. That
3158 waitpid won't return an exit status until the other threads
3159 in the group are reaped.
3161 - When a non-leader thread execs, that thread just vanishes
3162 without reporting an exit (so we'd hang if we waited for it
3163 explicitly in that case). The exec event is reported to
3167 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3169 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3171 errno
? safe_strerror (errno
) : "ERRNO-OK");
3175 linux_nat_debug_printf ("waitpid %ld received %s",
3177 status_to_str (status
).c_str ());
3179 linux_nat_filter_event (lwpid
, status
);
3180 /* Retry until nothing comes out of waitpid. A single
3181 SIGCHLD can indicate more than one child stopped. */
3185 /* Now that we've pulled all events out of the kernel, resume
3186 LWPs that don't have an interesting event to report. */
3187 iterate_over_lwps (minus_one_ptid
,
3188 [] (struct lwp_info
*info
)
3190 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3193 /* ... and find an LWP with a status to report to the core, if
3195 lp
= iterate_over_lwps (ptid
, status_callback
);
3199 /* Check for zombie thread group leaders. Those can't be reaped
3200 until all other threads in the thread group are. */
3201 check_zombie_leaders ();
3203 /* If there are no resumed children left, bail. We'd be stuck
3204 forever in the sigsuspend call below otherwise. */
3205 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3207 linux_nat_debug_printf ("exit (no resumed LWP)");
3209 ourstatus
->set_no_resumed ();
3211 restore_child_signals_mask (&prev_mask
);
3212 return minus_one_ptid
;
3215 /* No interesting event to report to the core. */
3217 if (target_options
& TARGET_WNOHANG
)
3219 linux_nat_debug_printf ("exit (ignore)");
3221 ourstatus
->set_ignore ();
3222 restore_child_signals_mask (&prev_mask
);
3223 return minus_one_ptid
;
3226 /* We shouldn't end up here unless we want to try again. */
3227 gdb_assert (lp
== NULL
);
3229 /* Block until we get an event reported with SIGCHLD. */
3235 status
= lp
->status
;
3238 if (!target_is_non_stop_p ())
3240 /* Now stop all other LWP's ... */
3241 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3243 /* ... and wait until all of them have reported back that
3244 they're no longer running. */
3245 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3248 /* If we're not waiting for a specific LWP, choose an event LWP from
3249 among those that have had events. Giving equal priority to all
3250 LWPs that have had events helps prevent starvation. */
3251 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3252 select_event_lwp (ptid
, &lp
, &status
);
3254 gdb_assert (lp
!= NULL
);
3256 /* Now that we've selected our final event LWP, un-adjust its PC if
3257 it was a software breakpoint, and we can't reliably support the
3258 "stopped by software breakpoint" stop reason. */
3259 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3260 && !USE_SIGTRAP_SIGINFO
)
3262 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3263 struct gdbarch
*gdbarch
= regcache
->arch ();
3264 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3270 pc
= regcache_read_pc (regcache
);
3271 regcache_write_pc (regcache
, pc
+ decr_pc
);
3275 /* We'll need this to determine whether to report a SIGSTOP as
3276 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3278 last_resume_kind
= lp
->last_resume_kind
;
3280 if (!target_is_non_stop_p ())
3282 /* In all-stop, from the core's perspective, all LWPs are now
3283 stopped until a new resume action is sent over. */
3284 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3288 resume_clear_callback (lp
);
3291 if (linux_target
->low_status_is_event (status
))
3293 linux_nat_debug_printf ("trap ptid is %s.",
3294 lp
->ptid
.to_string ().c_str ());
3297 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
3299 *ourstatus
= lp
->waitstatus
;
3300 lp
->waitstatus
.set_ignore ();
3303 *ourstatus
= host_status_to_waitstatus (status
);
3305 linux_nat_debug_printf ("exit");
3307 restore_child_signals_mask (&prev_mask
);
3309 if (last_resume_kind
== resume_stop
3310 && ourstatus
->kind () == TARGET_WAITKIND_STOPPED
3311 && WSTOPSIG (status
) == SIGSTOP
)
3313 /* A thread that has been requested to stop by GDB with
3314 target_stop, and it stopped cleanly, so report as SIG0. The
3315 use of SIGSTOP is an implementation detail. */
3316 ourstatus
->set_stopped (GDB_SIGNAL_0
);
3319 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
3320 || ourstatus
->kind () == TARGET_WAITKIND_SIGNALLED
)
3323 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3325 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
)
3326 return filter_exit_event (lp
, ourstatus
);
3331 /* Resume LWPs that are currently stopped without any pending status
3332 to report, but are resumed from the core's perspective. */
3335 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3339 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3340 lp
->ptid
.to_string ().c_str ());
3342 else if (!lp
->resumed
)
3344 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3345 lp
->ptid
.to_string ().c_str ());
3347 else if (lwp_status_pending_p (lp
))
3349 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3350 lp
->ptid
.to_string ().c_str ());
3354 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3355 struct gdbarch
*gdbarch
= regcache
->arch ();
3359 CORE_ADDR pc
= regcache_read_pc (regcache
);
3360 int leave_stopped
= 0;
3362 /* Don't bother if there's a breakpoint at PC that we'd hit
3363 immediately, and we're not waiting for this LWP. */
3364 if (!lp
->ptid
.matches (wait_ptid
))
3366 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3372 linux_nat_debug_printf
3373 ("resuming stopped-resumed LWP %s at %s: step=%d",
3374 lp
->ptid
.to_string ().c_str (), paddress (gdbarch
, pc
),
3377 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3380 catch (const gdb_exception_error
&ex
)
3382 if (!check_ptrace_stopped_lwp_gone (lp
))
3391 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3392 target_wait_flags target_options
)
3396 linux_nat_debug_printf ("[%s], [%s]", ptid
.to_string ().c_str (),
3397 target_options_to_string (target_options
).c_str ());
3399 /* Flush the async file first. */
3400 if (target_is_async_p ())
3401 async_file_flush ();
3403 /* Resume LWPs that are currently stopped without any pending status
3404 to report, but are resumed from the core's perspective. LWPs get
3405 in this state if we find them stopping at a time we're not
3406 interested in reporting the event (target_wait on a
3407 specific_process, for example, see linux_nat_wait_1), and
3408 meanwhile the event became uninteresting. Don't bother resuming
3409 LWPs we're not going to wait for if they'd stop immediately. */
3410 if (target_is_non_stop_p ())
3411 iterate_over_lwps (minus_one_ptid
,
3412 [=] (struct lwp_info
*info
)
3414 return resume_stopped_resumed_lwps (info
, ptid
);
3417 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3419 /* If we requested any event, and something came out, assume there
3420 may be more. If we requested a specific lwp or process, also
3421 assume there may be more. */
3422 if (target_is_async_p ()
3423 && ((ourstatus
->kind () != TARGET_WAITKIND_IGNORE
3424 && ourstatus
->kind () != TARGET_WAITKIND_NO_RESUMED
)
3425 || ptid
!= minus_one_ptid
))
3434 kill_one_lwp (pid_t pid
)
3436 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3439 kill_lwp (pid
, SIGKILL
);
3441 if (debug_linux_nat
)
3443 int save_errno
= errno
;
3445 linux_nat_debug_printf
3446 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3447 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3450 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3453 ptrace (PTRACE_KILL
, pid
, 0, 0);
3454 if (debug_linux_nat
)
3456 int save_errno
= errno
;
3458 linux_nat_debug_printf
3459 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3460 save_errno
? safe_strerror (save_errno
) : "OK");
3464 /* Wait for an LWP to die. */
3467 kill_wait_one_lwp (pid_t pid
)
3471 /* We must make sure that there are no pending events (delayed
3472 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3473 program doesn't interfere with any following debugging session. */
3477 res
= my_waitpid (pid
, NULL
, __WALL
);
3478 if (res
!= (pid_t
) -1)
3480 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3482 /* The Linux kernel sometimes fails to kill a thread
3483 completely after PTRACE_KILL; that goes from the stop
3484 point in do_fork out to the one in get_signal_to_deliver
3485 and waits again. So kill it again. */
3491 gdb_assert (res
== -1 && errno
== ECHILD
);
3494 /* Callback for iterate_over_lwps. */
3497 kill_callback (struct lwp_info
*lp
)
3499 kill_one_lwp (lp
->ptid
.lwp ());
3503 /* Callback for iterate_over_lwps. */
3506 kill_wait_callback (struct lwp_info
*lp
)
3508 kill_wait_one_lwp (lp
->ptid
.lwp ());
3512 /* Kill the fork children of any threads of inferior INF that are
3513 stopped at a fork event. */
3516 kill_unfollowed_fork_children (struct inferior
*inf
)
3518 for (thread_info
*thread
: inf
->non_exited_threads ())
3520 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3522 if (ws
->kind () == TARGET_WAITKIND_FORKED
3523 || ws
->kind () == TARGET_WAITKIND_VFORKED
)
3525 ptid_t child_ptid
= ws
->child_ptid ();
3526 int child_pid
= child_ptid
.pid ();
3527 int child_lwp
= child_ptid
.lwp ();
3529 kill_one_lwp (child_lwp
);
3530 kill_wait_one_lwp (child_lwp
);
3532 /* Let the arch-specific native code know this process is
3534 linux_target
->low_forget_process (child_pid
);
3540 linux_nat_target::kill ()
3542 /* If we're stopped while forking and we haven't followed yet,
3543 kill the other task. We need to do this first because the
3544 parent will be sleeping if this is a vfork. */
3545 kill_unfollowed_fork_children (current_inferior ());
3547 if (forks_exist_p ())
3548 linux_fork_killall ();
3551 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3553 /* Stop all threads before killing them, since ptrace requires
3554 that the thread is stopped to successfully PTRACE_KILL. */
3555 iterate_over_lwps (ptid
, stop_callback
);
3556 /* ... and wait until all of them have reported back that
3557 they're no longer running. */
3558 iterate_over_lwps (ptid
, stop_wait_callback
);
3560 /* Kill all LWP's ... */
3561 iterate_over_lwps (ptid
, kill_callback
);
3563 /* ... and wait until we've flushed all events. */
3564 iterate_over_lwps (ptid
, kill_wait_callback
);
3567 target_mourn_inferior (inferior_ptid
);
3571 linux_nat_target::mourn_inferior ()
3573 int pid
= inferior_ptid
.pid ();
3575 purge_lwp_list (pid
);
3577 close_proc_mem_file (pid
);
3579 if (! forks_exist_p ())
3580 /* Normal case, no other forks available. */
3581 inf_ptrace_target::mourn_inferior ();
3583 /* Multi-fork case. The current inferior_ptid has exited, but
3584 there are other viable forks to debug. Delete the exiting
3585 one and context-switch to the first available. */
3586 linux_fork_mourn_inferior ();
3588 /* Let the arch-specific native code know this process is gone. */
3589 linux_target
->low_forget_process (pid
);
3592 /* Convert a native/host siginfo object, into/from the siginfo in the
3593 layout of the inferiors' architecture. */
3596 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3598 /* If the low target didn't do anything, then just do a straight
3600 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3603 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3605 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3609 static enum target_xfer_status
3610 linux_xfer_siginfo (enum target_object object
,
3611 const char *annex
, gdb_byte
*readbuf
,
3612 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3613 ULONGEST
*xfered_len
)
3617 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3619 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3620 gdb_assert (readbuf
|| writebuf
);
3622 pid
= inferior_ptid
.lwp ();
3624 pid
= inferior_ptid
.pid ();
3626 if (offset
> sizeof (siginfo
))
3627 return TARGET_XFER_E_IO
;
3630 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3632 return TARGET_XFER_E_IO
;
3634 /* When GDB is built as a 64-bit application, ptrace writes into
3635 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3636 inferior with a 64-bit GDB should look the same as debugging it
3637 with a 32-bit GDB, we need to convert it. GDB core always sees
3638 the converted layout, so any read/write will have to be done
3640 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3642 if (offset
+ len
> sizeof (siginfo
))
3643 len
= sizeof (siginfo
) - offset
;
3645 if (readbuf
!= NULL
)
3646 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3649 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3651 /* Convert back to ptrace layout before flushing it out. */
3652 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3655 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3657 return TARGET_XFER_E_IO
;
3661 return TARGET_XFER_OK
;
3664 static enum target_xfer_status
3665 linux_nat_xfer_osdata (enum target_object object
,
3666 const char *annex
, gdb_byte
*readbuf
,
3667 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3668 ULONGEST
*xfered_len
);
3670 static enum target_xfer_status
3671 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3672 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3674 enum target_xfer_status
3675 linux_nat_target::xfer_partial (enum target_object object
,
3676 const char *annex
, gdb_byte
*readbuf
,
3677 const gdb_byte
*writebuf
,
3678 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3680 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3681 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3682 offset
, len
, xfered_len
);
3684 /* The target is connected but no live inferior is selected. Pass
3685 this request down to a lower stratum (e.g., the executable
3687 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3688 return TARGET_XFER_EOF
;
3690 if (object
== TARGET_OBJECT_AUXV
)
3691 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3692 offset
, len
, xfered_len
);
3694 if (object
== TARGET_OBJECT_OSDATA
)
3695 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3696 offset
, len
, xfered_len
);
3698 if (object
== TARGET_OBJECT_MEMORY
)
3700 /* GDB calculates all addresses in the largest possible address
3701 width. The address width must be masked before its final use
3702 by linux_proc_xfer_partial.
3704 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3705 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3707 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3708 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3710 /* If /proc/pid/mem is writable, don't fallback to ptrace. If
3711 the write via /proc/pid/mem fails because the inferior execed
3712 (and we haven't seen the exec event yet), a subsequent ptrace
3713 poke would incorrectly write memory to the post-exec address
3714 space, while the core was trying to write to the pre-exec
3716 if (proc_mem_file_is_writable ())
3717 return linux_proc_xfer_memory_partial (readbuf
, writebuf
,
3718 offset
, len
, xfered_len
);
3721 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3722 offset
, len
, xfered_len
);
3726 linux_nat_target::thread_alive (ptid_t ptid
)
3728 /* As long as a PTID is in lwp list, consider it alive. */
3729 return find_lwp_pid (ptid
) != NULL
;
3732 /* Implement the to_update_thread_list target method for this
3736 linux_nat_target::update_thread_list ()
3738 /* We add/delete threads from the list as clone/exit events are
3739 processed, so just try deleting exited threads still in the
3741 delete_exited_threads ();
3743 /* Update the processor core that each lwp/thread was last seen
3745 for (lwp_info
*lwp
: all_lwps ())
3747 /* Avoid accessing /proc if the thread hasn't run since we last
3748 time we fetched the thread's core. Accessing /proc becomes
3749 noticeably expensive when we have thousands of LWPs. */
3750 if (lwp
->core
== -1)
3751 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3756 linux_nat_target::pid_to_str (ptid_t ptid
)
3759 && (ptid
.pid () != ptid
.lwp ()
3760 || num_lwps (ptid
.pid ()) > 1))
3761 return string_printf ("LWP %ld", ptid
.lwp ());
3763 return normal_pid_to_str (ptid
);
3767 linux_nat_target::thread_name (struct thread_info
*thr
)
3769 return linux_proc_tid_get_name (thr
->ptid
);
3772 /* Accepts an integer PID; Returns a string representing a file that
3773 can be opened to get the symbols for the child process. */
3776 linux_nat_target::pid_to_exec_file (int pid
)
3778 return linux_proc_pid_to_exec_file (pid
);
3781 /* Object representing an /proc/PID/mem open file. We keep one such
3782 file open per inferior.
3784 It might be tempting to think about only ever opening one file at
3785 most for all inferiors, closing/reopening the file as we access
3786 memory of different inferiors, to minimize number of file
3787 descriptors open, which can otherwise run into resource limits.
3788 However, that does not work correctly -- if the inferior execs and
3789 we haven't processed the exec event yet, and, we opened a
3790 /proc/PID/mem file, we will get a mem file accessing the post-exec
3791 address space, thinking we're opening it for the pre-exec address
3792 space. That is dangerous as we can poke memory (e.g. clearing
3793 breakpoints) in the post-exec memory by mistake, corrupting the
3794 inferior. For that reason, we open the mem file as early as
3795 possible, right after spawning, forking or attaching to the
3796 inferior, when the inferior is stopped and thus before it has a
3799 Note that after opening the file, even if the thread we opened it
3800 for subsequently exits, the open file is still usable for accessing
3801 memory. It's only when the whole process exits or execs that the
3802 file becomes invalid, at which point reads/writes return EOF. */
3807 proc_mem_file (ptid_t ptid
, int fd
)
3808 : m_ptid (ptid
), m_fd (fd
)
3810 gdb_assert (m_fd
!= -1);
3815 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem",
3816 m_fd
, m_ptid
.pid (), m_ptid
.lwp ());
3820 DISABLE_COPY_AND_ASSIGN (proc_mem_file
);
3828 /* The LWP this file was opened for. Just for debugging
3832 /* The file descriptor. */
3836 /* The map between an inferior process id, and the open /proc/PID/mem
3837 file. This is stored in a map instead of in a per-inferior
3838 structure because we need to be able to access memory of processes
3839 which don't have a corresponding struct inferior object. E.g.,
3840 with "detach-on-fork on" (the default), and "follow-fork parent"
3841 (also default), we don't create an inferior for the fork child, but
3842 we still need to remove breakpoints from the fork child's
3844 static std::unordered_map
<int, proc_mem_file
> proc_mem_file_map
;
3846 /* Close the /proc/PID/mem file for PID. */
3849 close_proc_mem_file (pid_t pid
)
3851 proc_mem_file_map
.erase (pid
);
3854 /* Open the /proc/PID/mem file for the process (thread group) of PTID.
3855 We actually open /proc/PID/task/LWP/mem, as that's the LWP we know
3856 exists and is stopped right now. We prefer the
3857 /proc/PID/task/LWP/mem form over /proc/LWP/mem to avoid tid-reuse
3858 races, just in case this is ever called on an already-waited
3862 open_proc_mem_file (ptid_t ptid
)
3864 auto iter
= proc_mem_file_map
.find (ptid
.pid ());
3865 gdb_assert (iter
== proc_mem_file_map
.end ());
3868 xsnprintf (filename
, sizeof filename
,
3869 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3871 int fd
= gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0).release ();
3875 warning (_("opening /proc/PID/mem file for lwp %d.%ld failed: %s (%d)"),
3876 ptid
.pid (), ptid
.lwp (),
3877 safe_strerror (errno
), errno
);
3881 proc_mem_file_map
.emplace (std::piecewise_construct
,
3882 std::forward_as_tuple (ptid
.pid ()),
3883 std::forward_as_tuple (ptid
, fd
));
3885 linux_nat_debug_printf ("opened fd %d for lwp %d.%ld",
3886 fd
, ptid
.pid (), ptid
.lwp ());
3889 /* Helper for linux_proc_xfer_memory_partial and
3890 proc_mem_file_is_writable. FD is the already opened /proc/pid/mem
3891 file, and PID is the pid of the corresponding process. The rest of
3892 the arguments are like linux_proc_xfer_memory_partial's. */
3894 static enum target_xfer_status
3895 linux_proc_xfer_memory_partial_fd (int fd
, int pid
,
3896 gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3897 ULONGEST offset
, LONGEST len
,
3898 ULONGEST
*xfered_len
)
3902 gdb_assert (fd
!= -1);
3904 /* Use pread64/pwrite64 if available, since they save a syscall and can
3905 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3906 debugging a SPARC64 application). */
3908 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3909 : pwrite64 (fd
, writebuf
, len
, offset
));
3911 ret
= lseek (fd
, offset
, SEEK_SET
);
3913 ret
= (readbuf
? read (fd
, readbuf
, len
)
3914 : write (fd
, writebuf
, len
));
3919 linux_nat_debug_printf ("accessing fd %d for pid %d failed: %s (%d)",
3920 fd
, pid
, safe_strerror (errno
), errno
);
3921 return TARGET_XFER_E_IO
;
3925 /* EOF means the address space is gone, the whole process exited
3927 linux_nat_debug_printf ("accessing fd %d for pid %d got EOF",
3929 return TARGET_XFER_EOF
;
3934 return TARGET_XFER_OK
;
3938 /* Implement the to_xfer_partial target method using /proc/PID/mem.
3939 Because we can use a single read/write call, this can be much more
3940 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
3941 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
3944 static enum target_xfer_status
3945 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3946 ULONGEST offset
, LONGEST len
,
3947 ULONGEST
*xfered_len
)
3949 int pid
= inferior_ptid
.pid ();
3951 auto iter
= proc_mem_file_map
.find (pid
);
3952 if (iter
== proc_mem_file_map
.end ())
3953 return TARGET_XFER_EOF
;
3955 int fd
= iter
->second
.fd ();
3957 return linux_proc_xfer_memory_partial_fd (fd
, pid
, readbuf
, writebuf
, offset
,
3961 /* Check whether /proc/pid/mem is writable in the current kernel, and
3962 return true if so. It wasn't writable before Linux 2.6.39, but
3963 there's no way to know whether the feature was backported to older
3964 kernels. So we check to see if it works. The result is cached,
3965 and this is garanteed to be called once early at startup. */
3968 proc_mem_file_is_writable ()
3970 static gdb::optional
<bool> writable
;
3972 if (writable
.has_value ())
3975 writable
.emplace (false);
3977 /* We check whether /proc/pid/mem is writable by trying to write to
3978 one of our variables via /proc/self/mem. */
3980 int fd
= gdb_open_cloexec ("/proc/self/mem", O_RDWR
| O_LARGEFILE
, 0).release ();
3984 warning (_("opening /proc/self/mem file failed: %s (%d)"),
3985 safe_strerror (errno
), errno
);
3989 SCOPE_EXIT
{ close (fd
); };
3991 /* This is the variable we try to write to. Note OFFSET below. */
3992 volatile gdb_byte test_var
= 0;
3994 gdb_byte writebuf
[] = {0x55};
3995 ULONGEST offset
= (uintptr_t) &test_var
;
3996 ULONGEST xfered_len
;
3998 enum target_xfer_status res
3999 = linux_proc_xfer_memory_partial_fd (fd
, getpid (), nullptr, writebuf
,
4000 offset
, 1, &xfered_len
);
4002 if (res
== TARGET_XFER_OK
)
4004 gdb_assert (xfered_len
== 1);
4005 gdb_assert (test_var
== 0x55);
4013 /* Parse LINE as a signal set and add its set bits to SIGS. */
4016 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4018 int len
= strlen (line
) - 1;
4022 if (line
[len
] != '\n')
4023 error (_("Could not parse signal set: %s"), line
);
4031 if (*p
>= '0' && *p
<= '9')
4033 else if (*p
>= 'a' && *p
<= 'f')
4034 digit
= *p
- 'a' + 10;
4036 error (_("Could not parse signal set: %s"), line
);
4041 sigaddset (sigs
, signum
+ 1);
4043 sigaddset (sigs
, signum
+ 2);
4045 sigaddset (sigs
, signum
+ 3);
4047 sigaddset (sigs
, signum
+ 4);
4053 /* Find process PID's pending signals from /proc/pid/status and set
4057 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4058 sigset_t
*blocked
, sigset_t
*ignored
)
4060 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4062 sigemptyset (pending
);
4063 sigemptyset (blocked
);
4064 sigemptyset (ignored
);
4065 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4066 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4067 if (procfile
== NULL
)
4068 error (_("Could not open %s"), fname
);
4070 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4072 /* Normal queued signals are on the SigPnd line in the status
4073 file. However, 2.6 kernels also have a "shared" pending
4074 queue for delivering signals to a thread group, so check for
4077 Unfortunately some Red Hat kernels include the shared pending
4078 queue but not the ShdPnd status field. */
4080 if (startswith (buffer
, "SigPnd:\t"))
4081 add_line_to_sigset (buffer
+ 8, pending
);
4082 else if (startswith (buffer
, "ShdPnd:\t"))
4083 add_line_to_sigset (buffer
+ 8, pending
);
4084 else if (startswith (buffer
, "SigBlk:\t"))
4085 add_line_to_sigset (buffer
+ 8, blocked
);
4086 else if (startswith (buffer
, "SigIgn:\t"))
4087 add_line_to_sigset (buffer
+ 8, ignored
);
4091 static enum target_xfer_status
4092 linux_nat_xfer_osdata (enum target_object object
,
4093 const char *annex
, gdb_byte
*readbuf
,
4094 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4095 ULONGEST
*xfered_len
)
4097 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4099 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4100 if (*xfered_len
== 0)
4101 return TARGET_XFER_EOF
;
4103 return TARGET_XFER_OK
;
4106 std::vector
<static_tracepoint_marker
>
4107 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4109 char s
[IPA_CMD_BUF_SIZE
];
4110 int pid
= inferior_ptid
.pid ();
4111 std::vector
<static_tracepoint_marker
> markers
;
4113 ptid_t ptid
= ptid_t (pid
, 0);
4114 static_tracepoint_marker marker
;
4119 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
4120 s
[sizeof ("qTfSTM")] = 0;
4122 agent_run_command (pid
, s
, strlen (s
) + 1);
4125 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4131 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4133 if (strid
== NULL
|| marker
.str_id
== strid
)
4134 markers
.push_back (std::move (marker
));
4136 while (*p
++ == ','); /* comma-separated list */
4138 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
4139 s
[sizeof ("qTsSTM")] = 0;
4140 agent_run_command (pid
, s
, strlen (s
) + 1);
4147 /* target_can_async_p implementation. */
4150 linux_nat_target::can_async_p ()
4152 /* This flag should be checked in the common target.c code. */
4153 gdb_assert (target_async_permitted
);
4155 /* Otherwise, this targets is always able to support async mode. */
4160 linux_nat_target::supports_non_stop ()
4165 /* to_always_non_stop_p implementation. */
4168 linux_nat_target::always_non_stop_p ()
4174 linux_nat_target::supports_multi_process ()
4180 linux_nat_target::supports_disable_randomization ()
4185 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4186 so we notice when any child changes state, and notify the
4187 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4188 above to wait for the arrival of a SIGCHLD. */
4191 sigchld_handler (int signo
)
4193 int old_errno
= errno
;
4195 if (debug_linux_nat
)
4196 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4198 if (signo
== SIGCHLD
)
4200 /* Let the event loop know that there are events to handle. */
4201 linux_nat_target::async_file_mark_if_open ();
4207 /* Callback registered with the target events file descriptor. */
4210 handle_target_event (int error
, gdb_client_data client_data
)
4212 inferior_event_handler (INF_REG_EVENT
);
4215 /* target_async implementation. */
4218 linux_nat_target::async (bool enable
)
4220 if (enable
== is_async_p ())
4223 /* Block child signals while we create/destroy the pipe, as their
4224 handler writes to it. */
4225 gdb::block_signals blocker
;
4229 if (!async_file_open ())
4230 internal_error ("creating event pipe failed.");
4232 add_file_handler (async_wait_fd (), handle_target_event
, NULL
,
4235 /* There may be pending events to handle. Tell the event loop
4241 delete_file_handler (async_wait_fd ());
4242 async_file_close ();
4246 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4250 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4254 linux_nat_debug_printf ("running -> suspending %s",
4255 lwp
->ptid
.to_string ().c_str ());
4258 if (lwp
->last_resume_kind
== resume_stop
)
4260 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4265 stop_callback (lwp
);
4266 lwp
->last_resume_kind
= resume_stop
;
4270 /* Already known to be stopped; do nothing. */
4272 if (debug_linux_nat
)
4274 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4275 linux_nat_debug_printf ("already stopped/stop_requested %s",
4276 lwp
->ptid
.to_string ().c_str ());
4278 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4279 lwp
->ptid
.to_string ().c_str ());
4286 linux_nat_target::stop (ptid_t ptid
)
4288 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
4289 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4292 /* When requests are passed down from the linux-nat layer to the
4293 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4294 used. The address space pointer is stored in the inferior object,
4295 but the common code that is passed such ptid can't tell whether
4296 lwpid is a "main" process id or not (it assumes so). We reverse
4297 look up the "main" process id from the lwp here. */
4299 struct address_space
*
4300 linux_nat_target::thread_address_space (ptid_t ptid
)
4302 struct lwp_info
*lwp
;
4303 struct inferior
*inf
;
4306 if (ptid
.lwp () == 0)
4308 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4310 lwp
= find_lwp_pid (ptid
);
4311 pid
= lwp
->ptid
.pid ();
4315 /* A (pid,lwpid,0) ptid. */
4319 inf
= find_inferior_pid (this, pid
);
4320 gdb_assert (inf
!= NULL
);
4324 /* Return the cached value of the processor core for thread PTID. */
4327 linux_nat_target::core_of_thread (ptid_t ptid
)
4329 struct lwp_info
*info
= find_lwp_pid (ptid
);
4336 /* Implementation of to_filesystem_is_local. */
4339 linux_nat_target::filesystem_is_local ()
4341 struct inferior
*inf
= current_inferior ();
4343 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4346 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4349 /* Convert the INF argument passed to a to_fileio_* method
4350 to a process ID suitable for passing to its corresponding
4351 linux_mntns_* function. If INF is non-NULL then the
4352 caller is requesting the filesystem seen by INF. If INF
4353 is NULL then the caller is requesting the filesystem seen
4354 by the GDB. We fall back to GDB's filesystem in the case
4355 that INF is non-NULL but its PID is unknown. */
4358 linux_nat_fileio_pid_of (struct inferior
*inf
)
4360 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4366 /* Implementation of to_fileio_open. */
4369 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4370 int flags
, int mode
, int warn_if_slow
,
4371 fileio_error
*target_errno
)
4377 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4378 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4380 *target_errno
= FILEIO_EINVAL
;
4384 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4385 filename
, nat_flags
, nat_mode
);
4387 *target_errno
= host_to_fileio_error (errno
);
4392 /* Implementation of to_fileio_readlink. */
4394 gdb::optional
<std::string
>
4395 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4396 fileio_error
*target_errno
)
4401 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4402 filename
, buf
, sizeof (buf
));
4405 *target_errno
= host_to_fileio_error (errno
);
4409 return std::string (buf
, len
);
4412 /* Implementation of to_fileio_unlink. */
4415 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4416 fileio_error
*target_errno
)
4420 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4423 *target_errno
= host_to_fileio_error (errno
);
4428 /* Implementation of the to_thread_events method. */
4431 linux_nat_target::thread_events (int enable
)
4433 report_thread_events
= enable
;
4436 linux_nat_target::linux_nat_target ()
4438 /* We don't change the stratum; this target will sit at
4439 process_stratum and thread_db will set at thread_stratum. This
4440 is a little strange, since this is a multi-threaded-capable
4441 target, but we want to be on the stack below thread_db, and we
4442 also want to be used for single-threaded processes. */
4445 /* See linux-nat.h. */
4448 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4457 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4460 memset (siginfo
, 0, sizeof (*siginfo
));
4466 /* See nat/linux-nat.h. */
4469 current_lwp_ptid (void)
4471 gdb_assert (inferior_ptid
.lwp_p ());
4472 return inferior_ptid
;
4475 void _initialize_linux_nat ();
4477 _initialize_linux_nat ()
4479 add_setshow_boolean_cmd ("linux-nat", class_maintenance
,
4480 &debug_linux_nat
, _("\
4481 Set debugging of GNU/Linux native target."), _(" \
4482 Show debugging of GNU/Linux native target."), _(" \
4483 When on, print debug messages relating to the GNU/Linux native target."),
4485 show_debug_linux_nat
,
4486 &setdebuglist
, &showdebuglist
);
4488 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4489 &debug_linux_namespaces
, _("\
4490 Set debugging of GNU/Linux namespaces module."), _("\
4491 Show debugging of GNU/Linux namespaces module."), _("\
4492 Enables printf debugging output."),
4495 &setdebuglist
, &showdebuglist
);
4497 /* Install a SIGCHLD handler. */
4498 sigchld_action
.sa_handler
= sigchld_handler
;
4499 sigemptyset (&sigchld_action
.sa_mask
);
4500 sigchld_action
.sa_flags
= SA_RESTART
;
4502 /* Make it the default. */
4503 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4505 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4506 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4507 sigdelset (&suspend_mask
, SIGCHLD
);
4509 sigemptyset (&blocked_mask
);
4511 lwp_lwpid_htab_create ();
4513 proc_mem_file_is_writable ();
4517 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4518 the GNU/Linux Threads library and therefore doesn't really belong
4521 /* NPTL reserves the first two RT signals, but does not provide any
4522 way for the debugger to query the signal numbers - fortunately
4523 they don't change. */
4524 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4526 /* See linux-nat.h. */
4529 lin_thread_get_thread_signal_num (void)
4531 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4534 /* See linux-nat.h. */
4537 lin_thread_get_thread_signal (unsigned int i
)
4539 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4540 return lin_thread_signals
[i
];